At least 56 people have been killed in air attacks by the Syrian regime and Russian war planes on Eastern Ghouta, according to the White Helmets, a voluntary organization that operates in parts of opposition-controlled Syria.

On Monday night, at least 16 children and four women were reported killed after taking shelter in a school in the town of Irbin, which was hit by an air raid.

Activists told Al Jazeera that the deaths came as the regime bombardment of the enclave resumed following a brief lull.

Eastern Ghouta, which has been under opposition control since mid-2013, has been under a relentless bombing campaign, launched by Russian-backed Syrian forces a month ago.

According to the UN, hundreds of people have been killed as government forces and its Russian allies attempt to drive out armed opposition groups from Eastern Ghouta.

Activists and monitors say, however, the death toll is much higher, with some reporting as many as 1,400 killed.

Jaish al-Islam, one of the opposition groups in the area, launched a counterattack on Monday, activists said.

Al Jazeera's Zeina Khodr, reporting from Beirut in neighboring Lebanon, said that talks between the Russians and opposition fighters were "happening", but the renewed bombardment was an indication that negotiations were not "going well".

While the pro-regime alliance seeks a full surrender, opposition forces want a ceasefire deal, our correspondent said.

"They are now in a weak position, and are shrinking in opposition-controlled territories under heavy fire, particularly in the town of Douma … and Irbin," she said.

'War crimes'

Though thousands have fled to various shelters in regime-controlled territories, some 340,000 remain trapped inside, suffering from acute food shortages and a lack of medical supplies, the activists told Al Jazeera.

People in Eastern Ghouta have been appealing for international support and for monitors to be deployed on the ground to ensure their safety and protection in case regime forces seize more territory in the enclave.

The pro-regime alliance considers the latest operation as a victory, Al Jazeera's Khodr said, while human rights organizations express concern over missing civilians.

Lama Fakih, Human Rights Watch's deputy Middle East director, told Al Jazeera that in order to ensure the security of people fleeing from Eastern Ghouta, "we do need to have monitors on the ground".

"No one needs to be reminded of the violations that we have seen in places of detention by government forces," she said.

"From torture, to ill-treatment, to sexual violence and even executions."

Fakih's statement comes as activists inside the enclave report the arrest of many who attempted to flee to regime-controlled territories.

The United Nations human rights chief has said the siege of Eastern Ghouta "has involved pervasive war crimes", citing the "use of chemical weaponry, enforced starvation as a weapon of warfare, and the denial of essential and lifesaving aid, culminating in the current, relentless, month-long bombardment".
Zeid Ra'ad al-Hussein made the remarks during an informal meeting of the UN Security Council on Monday after a Russia procedural maneuver blocked him from speaking to a formal meeting.

Al-Jazeera