Syria’s army has broken Isil’s two-year siege on an airbase in eastern Aleppo, marking the first major success for a military campaign backed by Russia and Iran.

State television said on Tuesday that regime troops had reached the Kweiris airbase and were in the process of securing it.

Almost a thousand soldiers had been trapped on the base, surviving through air drops of food and munitions.

Kweiris was home to the first jets used by the Syrian regime to target anti-government protesters in July 2012. But under siege it had become a morgue for soldiers who died on the base, prompting rare protests in a key regime stronghold, Tartus, that demanded the bodies were brought home.

An AFP photographer at the scene on Tuesday said soldiers had broken through Islamic State of Iraq and the Levant (Isil) lines west of the base and reached the troops inside.

Syrian and Iranian troops backed by Iraqi militia launched a major offensive to reach Kweiris last month, backed by Russian air strikes.

Moscow intervened militarily in Syria’s war at the end of September, launching hundreds of air strikes against rebel groups fighting the Syrian president, Bashar al-Assad, and backing regime offensives on half a dozen fronts across the country.

These have mostly stuttered as Saudi Arabia, Turkey and Qatar have poured in anti-tank and other heavy weapons in support of vetted rebel groups.

The recapture of the airbase marks the first major victory of this campaign, and banishes the looming spectre of a massacre. Isil had taunted personnel there with threats of slaughter, sending leaflets to remind them of the fate of hundreds of soldiers executed when the extremist group overran another air base, Taqba in Raqqa province, last year.

But the victory was bittersweet, coming as the regime’s coastal heartland of Latakia suffered one of its bloodiest attacks since the beginning of Syria’s conflict. The Syrian Observatory for Human Rights, a monitoring group, said that at least 23 people were killed and another 40 wounded in two explosions.

The blasts hit two separate areas of the city, one from rocket fire and the other either from a rocket or a planted explosive device, the Britain-based Observatory said.

Home to many members from Mr Assad’s Alawite sect, Latakia has been spared much of the pain of a war which has killed over a quarter of a million people in four and a half years.

Russia’s intervention is understood to have been prompted by fears that rebel forces were pushing towards the area.