UN warns that rebel-held eastern Aleppo will be completely destroyed by Christmas as Russia boasts their military campaign has demonstrated the 'effectiveness' of its bombs 

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The UN's envoy to Syria has made an impassioned plea to save eastern Aleppo, warning the city faces total destruction, and urging Islamist fighters to leave so civilians can get aid.

Staffan de Mistura today warned that the city could be completely destroyed by Christmas.

'In maximum two months, two and a half months, the city of eastern Aleppo at this rate may be totally destroyed', he told reporters in Geneva.

The rebel-held eastern part of Aleppo has been hammered by a Russian-backed government offensive, with multiple attacks on hospitals.

Mr De Mistura said that the presence of Al-Nusra fighters in the city has been used as a justification by Moscow and Damascus for the continued assault.

The former Al-Nusra Front has recently changed its name to Fateh al-Sham Front following a break with Al-Qaeda, but many still see the two groups as tied.

'Can you please look at my eyes', Mr de Mistura said in a direct appeal to Nusra leaders, before pleading with them to quit Aleppo.

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Members of the Syrian opposition group attack with missiles Assad regime forces during an operation named 'Conquest of Aleppo' around Baskoy village in Aleppo

A deadly blast after a Russian Army missile is dropped on a neighbourhood in Aleppo

'If you decide to leave in dignity and with your weapons... I personally am ready physically to accompany you,' the UN envoy said. 

The UN estimates that 275,000 civilians are under siege in east Aleppo, with aid deliveries all but impossible since government forces seized the last supply route in July.

Mr De Mistura accused Nusra fighters of holding 'hostage' desperate civilians in need of life saving relief by refusing to withdraw from the city.

In a second appeal to Russia and Syrian President Bashar al-Assad's government, the UN envoy asked if they were truly prepared to bring about the ruin of Aleppo, once Syria's economic powerhouse.

'Or, are you rather ready to announce an immediate and total aerial bombing halt if Nusra leaves?' Mr de Mistura asked. 

Smoke rises after an attack on the Darat Izza neighbourhood in Aleppo

It is estimated that 450 civilians have been killed in the war-torn city since September 19, the Syrian Observatory for Human Rights has stated

Mr De Mistura warned that eastern Aleppo risked joining the ranks of the 20th century's worst tragedies, making comparisons to the massacre at Srebrenica and the Rwandan genocide, saying that 376 people had been killed and more than 1,200 injured since the bombardments restarted.

The surge in fighting, including an attack on the area's biggest hospital, spurred the United States to suspend its cooperation with Russia on the Syrian peace effort.

Russia has denied all responsibility for hospital attacks in the city. 

However, Russian Defence Minister Defence Minister Sergei Shoigu has said Moscow's year-long bombing campaign in Syria has showcased the 'reliability' of Russian weaponry, as the Kremlin has helped stabilise the war-ravaged country.

'In that period we have managed to stabilise the situation in the country (and) liberate a significant part of the territory from armed international terrorist groups,' Shoigu told a conference.

'Many types of modern weapons produced in our country were tested in difficult desert conditions and generally have shown their reliability and effectiveness.'

The comments come as international anger grows over Moscow's air support for a ferocious regime assault on eastern Aleppo that has prompted accusations of potential war crimes.

Pictures of small explosions in the Darat Izza neighbourhood point to the use of cluster bombs, which many countries have outlawed

Smoke rises following the air strike, in a campaign by the Syrian government, backed by Russia, to reclaim rebel-held areas in Aleppo 

The United States on Monday suspended talks with Russia on a ceasefire in Syria in protest at Moscow stepping up its bombing campaign.

Russia launched its military operation in Syria last September to back up long-time ally Bashar al-Assad to Western ire, helping to shore up the regime's embattled forces.

Russia's military has denied repeated accusations that it has struck civilian targets in the country during its year-long offensive.

Moscow has used Syria as a testing-ground for a range of new weaponry including long-range missiles fired from ships, submarines and warplanes.

Those include the X-101 rocket that has a range of 4,500 kilometres (2,800 miles) and was fired from bombers that took off from bases in Russia, Shoigu said.

Built on the foundations of its Soviet-era predecessor, Russia's arms industry is a key source of income for the country and brought in some $14.5 billion (13 billion euros) in 2015.

Yesterday, Syria's military announced it would be reducing its air strikes and artillery fire on rebels in the war-torn city of Aleppo - as a strike obliterated a residential area and pictures suggested the use of cluster bombs.

Government forces claimed they would reduce strikes to 'allow civilians to reach safe areas'. 

The announcement came on a day when a top official in Syria's main opposition also said violence in the city was reaching 'genocidal proportions'.

Images taken on Wednesday revealed large blasts in the Darat Izza neighbourhood caused by a Russian missile.

And a series of smaller explosions suggest the use of cluster bombs - a day after a four-year-old girl died in Aleppo having picked one up thinking it was a toy. 

A statement carried by state news agency SANA said the decision to reduce air strikes had been taken 'after the success of our armed forces in Aleppo and cutting off all terrorist supply routes into the eastern districts'.

On September 22, the army of Syrian President Bashar al-Assad announced a major assault to capture the opposition-held half of Aleppo

Smoke rising in a circular pattern above the residential area of the Darat Izza neighbourhood in Aleppo suggests the use of cluster bombs

It continued: 'The military command has decided to reduce the number of air strikes and artillery on terrorist positions to allow civilians that want to leave to reach safe areas.'

Opposition official Bassma Kodmani, of the High Negotiations Committee - a key player in UN-mediated peace talks that failed in April - said the city is not about to fall.

She said:  'We are not talking about a fall of Aleppo within days or even two to three weeks.'

Instead, Kodmani said the campaign had involved 'a level of violence against citizens that is reaching genocidal proportions'. 

Members of the Syrian opposition to President Bashar al-Assad launch a missile attack against government forces

On September 22, the army of Syrian President Bashar al-Assad announced a major assault to capture the opposition-held half.

Backed by Russian warplanes, the offensive is being waged in the city centre, in the northern outskirts, and in the southern edges.

It has come under international scrutiny because of indiscriminate air strikes on civilian infrastructure, including hospitals.

Heavy bombardment on Monday destroyed the M10 hospital, the largest in the eastern districts. 

Eman, the four-year-old who died after picking up a cluster bomb thinking it was a toy 

A four-year-old girl has died in Aleppo after picking up what she thought was a shiny toy, but which was actually a cluster bomb.

The tragedy happened while the young girl was collecting water in the under-siege Syrian city, which government forces, backed by Russia, are trying to reclaim from rebels.

Four-year-old Eman picked up a cluster bomb thinking it was a silver ball. She died as a result of her injuries after it exploded and shrapnel tore through her body

As soon as tiny Eman picked the object up to play, it exploded. 

Shrapnel tore through her tiny frame, and both of Eman's legs were broken in the blast.

Her doctor told ITV that her family and paramedics had said she thought the deadly weapon was a toy.