Ukraine crisis: Key players in eastern unrest
Eastern Ukraine is gripped by an armed separatist uprising, with pro-Russian protesters occupying government buildings in more than a dozen towns and cities, despite an ongoing "anti-terror" operation launched by the Ukrainian military.
The trouble started after pro-EU protesters forced out the Kremlin-backed government in Kiev, and Russia annexed the Crimean peninsula in March.
Here we have profiled some of the key figures involved on both sides of the growing unrest.
Rinat Akhmetov has finally made his position on Ukraine's crisis clear. After months apparently sitting on the fence, the tycoon is throwing his considerable resources behind a united Ukraine and against the separatists, who he says are threatening a "genocide".
The 47-year-old, whose fortune is estimated at more than $11bn (£6.5bn), is one of the most influential people in the Donbass - the industrial east of Ukraine - where the insurgency is at its peak.
He has as many as 300,000 people employed in his coal and steel enterprises across the region, according to Reuters news agency, and it is this workforce which he has shown he is willing to use as leverage.
He has called on his workers to lead the resistance to the separatists, by staging peaceful rallies daily. Such an initiative has already led to the rebels being chased out of the southern city of Mariupol.
Mr Akhmetov's allegiance had previously been unclear, since he was a close confidant of former President Viktor Yanukovych, and has business links with Russia.
Pavel Gubarev, the self-styled "people's governor" of Donetsk Region, was released from custody in Kiev on 7 May in exchange for three Ukrainian security service (SBU) officers held by pro-Russian militants in Sloviansk.
Mr Gubarev, the 31-year-old founder of an advertising company and a former Donetsk district council member from the fiercely pro-Russian Progressive Socialist Party of Ukraine, emerged from obscurity soon after the toppling of President Viktor Yanukovych in February.
Elected "people's governor" at a mass rally in Donetsk on 1 March, Mr Gubarev said that the people of Donbass (a historical region including Donetsk and Luhansk regions) were ready to "take power into their hands peacefully".
On 3 March, Mr Gubarev led the occupation of the regional administration building by hundreds of pro-Russian activists. He announced the formation of a provisional government and "people's militia", and called for a referendum on the region's status.
After his supporters were evicted from the building by police, Mr Gubarev was detained by Ukrainian security service officers in Donetsk on 6 March. The following day, a Kiev court remanded him in custody for two months. He faced charges of separatism and seizure of public buildings.
The Russian Foreign Ministry and State Duma have referred to Mr Gubarev as a "political prisoner" and repeatedly called for his release.
Photographs have been published on the internet indicating that he was an activist of the ultra-nationalist movement Russian National Unity in the past.
Vyacheslav Ponomaryov is the self-proclaimed pro-Russian mayor of Sloviansk, Donetsk region, the stronghold of the separatist movement in eastern Ukraine.
He is an opponent of the government in Kiev, which he calls a "junta".
Mr Ponomaryov is often seen travelling through Sloviansk in a car without a registration plate, accompanied by men armed with machine guns.
He was not a well-known figure before the recent unrest, so there is little credible information available about him. It is believed he ran a small soap factory in the region.
There are also unconfirmed reports that he fought as a Soviet soldier in Afghanistan in 1980s and has connections to the Russian special forces.
Recently he asked Russia President Vladimir Putin to send a Russian peacekeeping mission to eastern Ukraine.
He was involved in the seizure of a group of military observers from the Organization for Security and Co-operation in Europe (OSCE) and members of Ukraine's security service. The hostages were only released after growing pressure from the West and some involvement from Moscow.
Armed men under Mr Ponomaryov's command are still keeping a number of hostages, including journalists and pro-Ukrainian activists.
One of the best-known leaders of the uprising, Igor Strelkov directs armed pro-Russian activists in eastern Ukraine, especially in Sloviansk.
The Ukrainian security service says he works for the Russian military intelligence agency, the GRU, and his real name is Igor Girkin. He was born in 1970 and registered in Moscow, according to the service.
He is accused of playing a key role in abducting and murdering two pro-Ukrainian activists, including a local lawmaker.
He was previously active in Crimea. In an interview with Russia's Komsomolskaya Pravda newspaper, Mr Strelkov said that his brigade in Sloviansk had been formed in Crimea from volunteers only, but most of them had combat experience fighting for the Russian armed forces in Chechnya, Central Asia, Yugoslavia, Iraq and even Syria.
According to various sources, Mr Strelkov himself also took part in conflicts in Yugoslavia as a volunteer, and in Chechnya under contract.
Russian media, however, dismiss any ongoing links with the Russian military - in fact they suggest he is a military enthusiast who specialises in historical re-enactment and staged recreations of battles.
They describe him as commander of Sloviansk's self-defence forces, but say he is not a GRU colonel, but rather a retired officer of the Russian Federal Security Service (FSB). His last role before retirement was reportedly with the FSB's Directorate for Combating International Terrorism.
One of the Ukrainian government's key figures in the east, Serhiy Taruta was appointed governor of the Donetsk region in order to assert its authority and quell the protests in the area.
Nevertheless, several towns have been taken over by pro-Russian protesters and armed men in unmarked uniforms.
He claims he never wanted to be a state governor. He is one of the founders of the transnational metallurgical corporation ISD.
Forbes Ukraine lists him among the wealthiest citizens of the country, estimating his fortune at $697m (£415m, 500m euros).
Mr Taruta has been working from one of the business centres of the city, while the Donetsk regional administration building remains occupied by protesters.
He says the ousted President Viktor Yanukovych and his close allies, who fled the country in February, play a crucial role in the separatist unrest in eastern Ukraine.
He believes their actions are aimed at disrupting the presidential elections scheduled for 25 May 2014.
Pro-Ukrainian activists have repeatedly accused him of not doing enough to tackle the separatists in the region.
Hennadiy Kernes has been mayor of Kharkiv since 2010.
He was shot and critically wounded by an unknown gunman in the city on 28 April 2014 and is now recovering in a hospital in Israel.
Mr Kernes was originally a supporter of President Yanukovych, but changed his stance in favour of the new government in Kiev after Mr Yanukovych was ousted.
He has recently backed the idea of a united Ukraine.
The mayor has been described as a "mini-oligarch" - a successful businessman wealthy enough to launch a career in politics.
He has been accused of starting his business career as an organised crime boss, a claim he denied while acknowledging that he was once jailed for fraud - a minor offence "partly fabricated" by his enemies, he insisted.
He is a close friend of Party of Regions presidential candidate Mikhail Dobkin.
Ukrainian PM Arseniy Yatsenyuk (left) and Ihor Kolomoisky
One of Ukraine's richest oligarchs has been in charge of the eastern Dnipropetrovsk region since March.
Despite the initial controversy surrounding the appointment, the 51-year-old is now widely credited with keeping the region with a large Russian-speaking population stable and largely violence-free.
Last month, he famously offered a $10,000 bounty to those who captured any Russian soldier - widely known in Ukraine as "little green men". He also promised to pay $1,000 for each machine gun handed over to the authorities.
In addition, Mr Kolomoisky offered - and on at least one occasion paid - significant financial rewards to Ukrainian troops who had successfully repelled attacks by separatists.
In retaliation, pro-Russian militants in the neighbouring Donetsk region have attacked and ransacked branches of PrivatBank, which are owned by Mr Kolomoisky.
The self-declared "people's governor" of the Luhansk region was a key player in forming militia units and the storming of the local security service building last month.
The former paratrooper, in his 40s, has also been actively pushing for a separatist referendum planned for 11 May.
Poroshenko, Ukraine's rescuer
Kosovo holds parliamentary elections
Egypt swears in new President Sisi
Barra Brava
Watch and learn 
E3 preview 
Go Figure
Zero gravity
The Travel Show