BEIRUT  - Warplanes bombed a Palestinian refugee camp in south Damascus on Sunday for the first time since the start of Syria’s more than 21-month conflict, the Syrian Observatory for Human Rights said.

The air strike killed at least eight civilians in the Yarmuk camp, which has been rocked by intermittent violence over the past few months, the Britain-based watchdog said, addding that others were in critical condition.

Palestinian president Mahmud Abbas appealed on Sunday for an immediate halt to firing on refugee camps. The Islamist Hamas movement also condemned the attacks, calling them a “crime.”

“We call on the warring sides in Syria to spare the Palestinian people and their camps in Syria,” he said in a statement carried by official Palestinian news agency WAFA, adding that bombing of the refugee camps “must be stopped immediately.”

“We also call on the international community to take immediate action to provide protection to our people in Syria,” Abbas said, adding that the Palestinians were “not involved” in the conflict.

In a statement on his official Facebook page, Izzat al-Rishq, of Hamas’s politburo-in-exile, described the attack on Yarmuk as a “crime.”

“We strongly condemn the continued exposure of Palestinian camps in Syria to targeting, aggression and bombing,” he wrote, under the headline: “On the crime of the targeting of Yarmuk camp by warplanes.”

The raid came hours after the rebel Free Syrian Army (FSA) made significant advances in Yarmuk, a camp resident told AFP by Internet.

“There is a state of real war in the camp now,” Abu Mohammed said. “There are intense battles between the Free Syrian Army and the Popular Front for the Liberation of Palestine-General Command,” a hardline Palestine group that has long been a Damascus ally.

“The air strike happened because of the FSA’s advances in the camp,” he said. “The two are obviously linked.”

PFLP-GC fighters were locked in fierce clashes with rebel units, some of them Palestinian, the Observatory said. The PFLP-GC, headed by Ahmed Jibril, has sided with the regime of President Bashar al-Assad throughout the revolt, while some Palestinians have fought alongside the rebels.

Residents told AFP that one missile hit the Abdel Qader Husseini Mosque in the heart of the camp, which was acting as a makeshift shelter for some 600 people who had fled homes in nearby districts.

Abu Mohammed said a second missile struck near a school housing hundreds more displaced people. The Observatory earlier reported that a toddler was killed in shelling of Yarmuk by the army. Activists in the camp said Yara Abu Shaira was not yet two years old.

Warplanes also bombarded the nearby districts of Al-Hajar al-Aswad and Assali, scene of intense fighting between troops and rebels, it added. On the ground, violence raged as at least 19 people were killed in air strikes across the country, among them six children, said the Observatory.  In the northern province of Aleppo, eight people including three children and two women died in air strikes on the town of Safira. Elsewhere, three children including one aged three were killed in air raids on the town of Kfar Zeita in the central province of Hama.

Just south of Kfar Zeita, six civilians were killed in shelling on Latamneh village and 23 people, including 15 civilians and eight rebels, died in clashes and regime bombardments on the town of Halfaya. Separately, rebels clashed with troops near an important military academy in Mulsimiyeh just north of the embattled city of Aleppo, said the Observatory.

Clashes raged “after the army deployed reinforcements” a day after rebels captured two thirds of the sprawling complex, it added.

The Observatory gave an initial toll of 52 people killed nationwide in Syria, adding to the total of more than 43,000 killed since the start of the uprising in March last year.