Islamic State (Isis) extremists have publicly beheaded four Syrian men in the eastern Deir ez-Zor province after they assisted women and children flee their self-declared caliphate, it has been claimed. The latest executions reportedly took place in the besieged al-Bukamal city, which sits on the Euphrates River in eastern Syria, near the border with Iraq.

According to local media reports, the men were caught helping a number of families escape the city. They were then said to be charged with "supporting enemies of the Caliphate" before they were executed in the city's Tayyara square.

In January this year, IS (Daesh) militants kidnapped at least 400 civilians in a raid on government-held areas in the city of Deir ez-Zor, according to British-based monitoring group the Syrian Observatory for Human Rights (SOHR).

The SOHR said the families of pro-government fighters had been seized by IS and that 135 people were killed in the attack, including 85 civilians and 50 pro-government fighters.

The latest killings were reported by media activist Samir al-Khallaf to the Kurdish ARA News agency. IBTimes UK could not independently verify the alleged executions.

"The ISIS-led Islamic Police in al-Bukamal captured the four young men and brought them to the Sharia Court, which decided to publicly execute them on Wednesday afternoon. The Isis court accused them of supporting the enemies of the so-called Caliphate," al-Khallaf reported.

He added that the four men were beheaded in front of hundreds of people in Tayyara.

Al-Bukamal has been under siege by western-backed Syrian rebel fighters for weeks. On 30 June, a photo report purportedly released by IS showed the feared al-Hisba religious police publicly whipping men accused of breaking their Ramadan fast in the city.

The latest executions came as two bomb blasts hit the northeastern Syrian city of Qamishli, near the Turkish border on 27 July. The twin explosions killed at least 44 people and wounded 170 others and was claimed by IS, who were targeting Kurdish security forces.