ISIS attack churches Syria
Flags of the al-Qaeda linked Islamic State of Iraq and the Levant are hung to replace crosses on The Martyrs Church in ar-Raqqah (Reuters)

Islamist rebels in Syria attacked two Christian churches in the city of ar-Raqqah, burning relics and breaking crosses.

Fighters from al-Qaida spinoff the Islamic State of Iraq and the Levant (Isis) stormed the Catholic Sayida al-Bshara church and the Armenian al-Shuhada' church, also known as Martyrs' Church,  in the northern rebel held city, Britain-based activist organisation the Syrian Observatory for Human Rights (SOHR) reported.

"Isis fighters broke the cross of the Sayida al-Bshara Catholic church," SOHR said. "They also burned the church's contents (crosses, paintings and statues) and set up the Isis banner on top of the church."

"Isis fighters also removed the cross from the al-Shuhada' Armenian church near the al-Rashid garden," the group added.

"We in the Syrian Observatory for Human Rights strongly condemn such sectarian actions that contradict the Syrian people's demands in justice, freedom, democracy and equality."

The Islamist grip over ar-Raqqah in northern Syria has fuelled tension and deadly clashes between the Islamist group, Kurdish factions and moderate rebel groups such as the Ahfad al-Rasul brigade.

ISIS is believed to be responsible for the abduction of Italian Priest Paolo Dall'Oglio, who vanished in the city in July.

The Jesuit missionary had reportedly voluntarily approached Isis at their headquarters to negotiate the release of some hostages and broker a truce between Islamist rebels and local Kurds.

Isis is a rebranding of al-Qaida's Iraqi branch, whose influence was curbed by US operations in Iraq after the 2003 war, but has recently regained momentum.

In recent months its followers have killed more people in Iraq than at any time since 2008, carrying out a spate of terrorist attacks and staging spectacular prison breaks. Isis eventually exploited the ongoing civil war to extend its reach into Syria.

Largely fuelled by foreign jihadist it has taken over control of large rebel-held areas, including ar-Raqqah.

Islamist rebel groups influence in Syria has dramatically grown in recent months.

Eleven extremist groups have recently signed a declaration announcing they do not recognise the authority of the main opposition alliance, the National Coalition.

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