Isis kills man in front of children and 'crucifies' body on roundabout in wave of executions in Raqqa

Activists said at least 10 people were executed in two days on charges including spying and burglary

Isis fighters parade in Raqqa, which became the group's de-facto capital in Syria in August 2014. (AP)

Isis has killed at least 10 people in just two days in Syria and displayed their bodies in gory mock crucifixions.

One man’s body was hung from a post on a busy roundabout in its de-facto capital of Raqqa, dressed in one of the orange jumpsuits that have become synonymous with the group’s execution videos.

Raqqa is Being Slaughtered Silently (RBSS), an activist group documenting atrocities in the city, said the man was murdered on Saturday on charges of being a spy.

Isis released the names and photos of eight other men who were killed in the town of al-Mansoura, in Raqqa province, saying it had killed them and crucified their bodies on charges of robbery and corruption.

RBSS counted 10 people executed over the weekend, including another man named as, Amen Souror, but other sources put the total as high as 15.

The UK-based Syrian Observatory of Human Rights documented one execution at the Tal Abyad roundabout in Raqqa, which it said was watched by dozens of civilians including children.

The group said there was conflicting information over whether the man, charged with espionage, had been a member of Isis or was arrested separately.

It confirmed news of the al-Mansoura executions, listing accusations of “corrupting on earth, and looting of Muslim’s money and forming a gang that impersonate al-Hisba members”, Isis’ feared religious police force.

The killings followed the arrest of 35 members of the so-called Islamic State, which were thought to be in connection with the assassination of senior figure Abu Hija al-Tunisi, who died in an air strike on Wednesday.

This reported crackdown came amid a series of new restrictions by Isis, which appears to be suffering the consequences of efforts by the US-led coalition to choke its revenue streams and infrastructure.

It has also been shaken by one of its biggest military defeats in Palmyra, which has been seized by regime forces, and death of one of its top commanders.

Militants are also reportedly forcing more people to undergo courses in its ideology and jihad, while rationing electricity and temporarily cutting off water supplies as the humanitarian situation in the city deteriorates further.

Fighters' salaries were cut according to a decree issued earlier this year and the group is said to have become increasingly reliant on the US dollar after a failed attempt to start its own currency.

Pressure was continuing to mount on the group on Sunday as Isis militants were driven out of the town of al-Qaryatayn by Syrian forces backed by Russian air strikes.

Troops loyal to Bashar al-Assad have been advancing from Palmyra, which they recaptured last Sunday, and are expected to push towards other strongholds including Deir Ezzor and Raqqa.

A fragile “cessation of hostilities” has held in Syria for over a month but Isis, Jabhat al-Nusra and other designated terrorist groups are not party to the truce.

Additional reporting by Reuters