Syrian government air strikes on destroyed ancient city Palmyra kill at least 26 people including 12 Islamic State militants

• More than 100 people have also been wounded in the heavy bombardment 
• City's only hospital suffering from severe shortages in staff and equipment 
• Palmyra has been listed as a world heritage site by UNESCO since 1980
• ISIS has destroyed a number of ancient temples since taking over the city

By Lydia Willgress for MailOnline

Published: 02:49 EST, 19 September 2015 | Updated: 06:53 EST, 19 September 2015

At least 26 people have died after the Syrian government unleashed a wave of air strikes on Islamic State-held city Palmyra.

Twelve militants from the extremist group are believed to be among those killed, the British-based Syrian Observatory for Human Rights reported.

More than 100 people have also been wounded in some of the heaviest air strikes since the extremist group seized the ancient town in May.

At least 26 people have died after the Syrian government unleashed a wave of air strikes on Islamic State-held city Palmyra. Above, a picture released by ISIS militants shows them destroying a 2,000-year-old temple in the city earlier this year

A local activist, who spoke on condition of anonymity for security reasons, reported at least 30 air raids on Friday. 

The city's only hospital was suffering severe shortages in staff and equipment, it was said.

Palmyra has been listed as a world heritage site by UNESCO since 1980.

ISIS, which has imposed a violent interpretation of Islamic law across a self-declared 'caliphate' straddling Syria and Iraq, claims ancient relics promote idolatry and has since razed the city to the ground. 

The group destroyed the Temple of Baalshamin and blew up the larger Temple of Bel at the end of August. 

Islamist insurgents also shot dead 56 members of Syrian government forces this week in a mass execution at an air base captured from the army.

The mass killing at Abu al-Duhur air base happened a few days ago, the Syrian Observatory for Human Rights added.

The air strikes come just one day after the Syrian army carried out heavy air raids in the northern city of Raqqa, also held by the Islamic State group. 

Palmyra was a jewel of the ancient world because its Greco-Roman ruins were so well preserved

Islamic State took over Palmyra in May, with the group releasing propaganda images, including this one (above) from the city ever since

Meanwhile, a coalition of rebel groups launched a major ground offensive on two predominantly Shiite villages in the northern province of Idlib. 

The groups, known as Army of Conquest, fired dozens of rockets and detonated at least seven booby-trapped vehicles on the outskirts of the area, which is held by pro-government forces.  

Syrian government forces have pulled out from Idlib province over the past year following major gains by the rebel coalition. 

The two villages that were attacked are the only remaining pro-government posts in the region. 

More than 250,000 people have died in Syria's civil war, according to UN officials.