Extremist fighters claiming to be from an al Qaeda-linked group have blown up a Shiite religious building in the Syrian province of Deir Ezzor, a watchdog said on Sunday.
The Syrian Observatory for Human Right said the attack occurred on Friday in the eastern village of Hatlah, where rebel fighters killed at least 60 Shiites earlier in the week.
"Videos show the destruction of a Shiite hussainiyah by the Islamic State of Iraq and the Levant in the village of Hatlah in Deir Ezzor," the group said.
"The destruction was apparently carried out the day before yesterday (Friday)," it added.
Two videos distributed by the Observatory showed fighters who identified themselves as belonging to the Islamic State of Iraq and the Levant inside the religious building, stepping on Shiite books.
The filming then continues from outside the building, as a powerful explosion rips through it to cries of praise from the fighters.
Several then run towards the rubble of the building, waving the black flag associated with extremist Islamist movements.
The Islamic State of Iraq and the Levant is the name for the group created by a merger between al Qaeda's Iraqi branch and the jihadist Syrian Al-Nusra Front.
But the merger, announced unexpectedly in April by the leader of the Islamic State of Iraq, Abu Bakr al-Baghdadi, was rejected by al Qaeda's top leadership and received cautiously by Nusra's chief.
Earlier this month, al Qaeda chief Ayman al-Zawahiri ruled that the Islamic State of Iraq and Nusra should operate independently, but on Saturday Baghdadi insisted the merger would proceed.
The destruction of the hussainiyah comes after fighting between rebels and armed Shiite residents of Hatlah on Tuesday, which left at least 60 Shiites dead, according to the Observatory.
The clashes came after Shiite militiamen from the predominantly Sunni village attacked a nearby rebel checkpoint, the group said.
At least 10 rebels were killed in the subsequent attack on Hatlah, and the fighting prompted most of the villages Shiite residents to flee.
On Saturday, activists said another Shiite religious building was burned by extremist fighters in a nearby village in Deir Ezzor, but there were no additional details on the incident.
The Syrian conflict pits a Sunni-led opposition against the regime dominated by Alawites, whose faith is an offshoot of Shiite Islam.
The fighting has taken on increasingly sectarian overtones, particularly with the entry into the conflict of extremist fighters from other Arab countries.