At least five senior Isis leaders have been killed in air strikes in Syria, US Central Command and the Russian Ministry of Defence have reported.

US-led coalition bombing dispatched two weapons experts in the east of Deir Ezzor on Thursday, a statement from the Combined Joint Task Force said.

Abu Anas al-Shami, who spearheaded Isis attempts to procure explosives used in terror attacks both inside and outside Syria, was killed near the city of Mayadin, coalition spokesperson Colonel Ryan Dillon told reporters at the Pentagon.

“He also oversaw the building of improvised explosives to rig corpses, vehicles and buildings to try and help Isis cling to strongholds they are losing in Iraq and Syria,” he added.

Junaid ur Rehman, a drone pilot who was skilled at modifying drones into weapons, was killed in the village of al-Ashara, just south of Mayadin.

Also in Deir Ezzor province – where with the help of Russian air power the Syrian army has managed to break an Isis siege on the town of the same name for the first time since the militants surrounded it three years ago – Russian jets reportedly killed more than 40 combatants in recent strikes, including four senior commanders who were meeting at an important underground command-and-control centre.

Isis’ war minister Gulmurod Khalimov – originally from Tajikistan – and the “Emir of Deir Ezzor” Abu Muhammad Al-Shmali, the organisation’s finance minister, were among the dead, the Russian defence ministry said on Friday.

Khalimov, the US-trained commander of Tajikistan’s elite police force, defected to Isis in April 2015 and later posted a video in which he vowed to return home to establish sharia law in his home country and take the holy jihad to Russia and the US.

Al-Shmali’s death has also previously been claimed by US forces.

“Effective actions of the Russian Aerospace Forces made it possible to speed up the unblocking of the city of Deir Ezzor and allow the Syrian troops to start its immediate liberation,” Moscow said in a statement.

The Syrian army and militias loyal to Syrian President Bashar al-Assad – led by General Suheil al-Hassan, known as “the Tiger” – managed to break through Isis’ defences for the first time on Tuesday.

On Thursday, comprehensive shipments reached the city’s besieged 70,000 civilians, who have been reliant for years on erratic UN airdrops of food and medicine.

Ousting Isis from Deir Ezzor will be the latest victory for Mr Assad, who has slowly gained the upper hand against Islamist and other rebel groups in Syria’s six-year-old war since Russia intervened in the conflict in 2015.

The militants are also under significant pressure in their de facto capital of Raqqa, south of Deir Ezzor, where the US-backed Arab and Kurdish Syrian Democratic Forces (SDF) has now retaken 6 per cent of the city in a battle which has seen significant civilian casualties.

The SDF is now preparing to take the jihadists on in the most well-defended neighbourhoods of the town.

Isis lost control of its largest city, Mosul in neighbouring Iraq, in July.

While Isis’ so-called caliphate across Syria and Iraq is crumbling, the organisation is expected to mount a fierce insurgency across both countries – and step up its terror attacks around the world.