AMMAN (Reuters) - The Syrian opposition delegation at peace talks in Vienna received a pledge on Friday from Russia that it would press the Syrian army to enforce a ceasefire in the besieged enclave of eastern Ghouta, an opposition spokesman said on Friday.

Syrian army and Russian jets have for the last two months been escalating their bombardment of the besieged rebel enclave near Damascus, killing dozens of civilians and injuring hundreds, rebels and aid workers say.

“There was a Russian pledge to the negotiating team ... It will begin at 12, after midnight today,” Ayman al Asemi, a member of the Free Syrian Army’s military council told Reuters.

However, the spokesman for the opposition’s negotiation committee at the Vienna talks, Yahya al-Aridi, did not confirm the Russian pledge, saying only: “There are negotiations about this.”

International concern has been rising over the fate of eastern Ghouta, where the United Nations says acute shortages of food and medicine have contributed to the worst malnutrition seen in the Syrian civil war.

The enclave is home to almost 400,000 people and is in an agreed “de-escalation zone” under Russian-led ceasefire deals for rebel-held territory, but the fighting there has continued.

On Wednesday Russia denied accusations that it and the Syrian army were behind a chemical attack in eastern Ghouta on Jan. 22.

(The role of Yahya al-Aridi was corrected in the story)