UNITED NATIONS — The morning after an aid convoy came under fire when it tried to reach a besieged Syrian city, a meeting here on a draft resolution that would force all parties in the bloody conflict to allow access for humanitarian organizations fell apart when representatives from Russia and China failed to show up, United Nations Security Council diplomats said.

On Monday afternoon, the Russian ambassador to the United Nations, Vitaly I. Churkin, did not directly say he would veto the draft if it came up for a vote, but called it “one of those political things” that would not be adopted by the Security Council. “This text would not have any practical, positive impact on the situation,” Mr. Churkin said.

The Chinese ambassador, Liu Jieyi, said Monday evening that he was concerned that a humanitarian resolution would disrupt the political talks underway in Geneva. “It’s a delicate process,” he said. He refused to say whether China would veto a proposed resolution.

A United Nations spokesman said that 11 people were killed as aid workers delivered food and medicine over the weekend to the Old City of Homs. About 800 people, mainly women, children and elderly people, have been evacuated so far, and some of them told United Nations officials that they had resorted to eating grass and weeds to survive.