Jaish al-Islam allegedly executes 10 IS fighters in video

One of Syria’s leading opposition groups has released a video of a mass execution of captured Islamic State fighters.

Jaish al-Islam (JAI), a major opposition groups primarily based in the Ghouta region of Damascus, released the video on Wednesday in which a group of 10 prisoners, purportedly from IS, are made to go down on their knees in the road and shot in the back of the head.

In the video, JAI fighters condemn IS as "dogs of hell" and "Khawarij," referring to the Muslim rebels who refused to follow either Ali or Aisha after the death of Muhammad.

"The most serious calamity of jihad today is a group of people who grow at a time of division among Muslims," says one fighter, standing over a kneeling prisoner.

"This group claimed to be the mother state and made takfir on other Muslims, shed their blood and looted their properties and dignities.

"They supported the enemy Shia and Nusayris, worsening the ordeal of Muslims by corrupting their religion and livelihood and killing the jihadi leaders who did their best to help our stricken nation."

The video also claims that after “investigations” it was discovered that “four senior ISIS commanders held a confidential meeting with four other high-ranking officers of the Syrian intelligence in Damascus”.

Many opponents of the Assad government in Syria have claimed that there is cooperation - both tacit and direct - between the Syrian army and IS.

Though Jaish al-Islam are regarded as being less extreme than IS, a number of statements made by the group’s leaders have been interpreted as sectarian.

In a video released in 2013, JAI leader Zahran Alloush warned that JAI will “wash the filth of the Rafida and the Rafidia [Shia] from Sham, they will wash it forever, if Allah wills it, until they cleanse Bilad al-Sham from the filth of the Majous [polytheists] who have fought the religion of Allah.”

In December 2013, the group was accused of committing a “massacre” of a number of Druze and Alawites in the central Syrian city of Adra.

However, there have been attempts by the group more recently to profess a commitment to pluralism in the country.

“We don't mean that all Syrian society must be from one religion or one type of people, this is impossible,” said JAI spokesperson Abdurrahman Saleh, speaking to Middle East Eye.

“For thousands of years all of these groups of people living in Syria and the Middle East in general, they have co-existed peacefully, so we don't want to change the demographic or social or religious formula of this society.”

In an interview with McClatchy newspaper in May, Alloush also seemed to backtrack on his earlier comments, referring to the Alawites as "part of the Syrian people".

Since its rise to power in Syria following the beginning of the country's civil war in 2011, IS has come into conflict with many other opposition groups, who resented its claim to authority over the Muslim world and its violent authoritarian tendencies.