Hundreds of people in Eastern Ghouta fled the advancing Syrian regime forces on Sunday amid the United Nations’ condemnation that the violence has continued unabated despite a ceasefire deal. The Syrian Observatory for Human Rights, a UK-based organization which reports on the war, estimated that between 300 to 400 families had fled, adding that regime bombardment was focused on the town of Mesraba. Regime forces are thrusting into the besieged rebel enclave from its eastern edge in an apparent bid to split it in two - a pattern of attack used repeatedly by Damascus and its allies in the war entering its eighth year. Orient TV, which supports the opposition to Bashar al-Assad, said advances by regime forces had triggered large-scale displacement. People were seeking shelter in areas closer to the center of the Eastern Ghouta, said the resident, who estimated thousands were on the move. Damascus, backed by Russia and Iran, has been waging one of the deadliest offensives of the war in Eastern Ghouta, killing hundreds of people in a fierce air and artillery bombardment over the last two weeks. Nearly 600 people have been killed and more than 2,000 injured since the assault began three weeks ago, said the UN. The UN Security Council demanded a 30-day countrywide ceasefire a week ago, but this has failed to take effect. Russia has instead called for daily, five-hour humanitarian ceasefires to allow for aid deliveries and evacuations of civilians and wounded. No aid has been delivered however, and the US State Department has called the Russian plan a “joke”. The Russian military said militants in Eastern Ghouta had imposed a curfew in areas under their control to prevent civilians from leaving through a humanitarian corridor during the truce, Interfax news agency reported. Rebel officials have consistently denied stopping civilians from leaving. Violence has escalated in Eastern Ghouta, despite the UN ceasefire call a week ago, and the bombing of the besieged Syrian enclave represents a "simply unacceptable" punishment of civilians, said UN regional humanitarian coordinator Panos Moumtzis on Sunday. "Instead of a much needed reprieve, we continue to see more fighting, more death, and more disturbing reports of hunger and hospitals being bombed. This collective punishment of civilians is simply unacceptable," he added in a statement. Earlier, a UN official in Syria told Reuters a humanitarian convoy carrying life-saving supplies from UN and other aid agencies would not enter Eastern Ghouta as had been planned on Sunday, citing a lack of permission. Western diplomats said that the regime had not given the final clearances needed for safe access. The convoy of some 40 trucks had been due to go to Douma in the regime-besieged enclave near Damascus, where some 400,000 people need food, medical and other supplies, the UN says. Only one small convoy with supplies for 7,200 people has been allowed to Ghouta so far this year, in mid-February. A Western diplomat, speaking on condition of anonymity, drew a parallel with rebel-held eastern Aleppo where no aid convoys were allowed to enter in late 2016 before it fell to regime forces: “Similar to the lack of approval to get aid into East Aleppo - lots of talk and no action.” The office of French President Emmanuel Macron says that he and UN Secretary-General Antonio Guterres are extremely worried about the continued violence in Eastern Ghouta despite the ceasefire resolution. Macrons office said in a statement that he and Guterres spoke Saturday and expressed their "grave concern" and called for a full implementation of the resolution. The statement added UN convoys should be delivering aid to hard-hit populations in the region.