In a powerful rebuke to Syria's government, the U.N. General Assembly voted overwhelmingly Thursday to approve a resolution condemning President Bashar Assad's unbridled crackdown on an 11-month-old uprising and called for the adoption of an Arab League proposal to resolve the conflict.

The 137-12 vote, with 17 abstentions, is a nonbinding action with no power of enforcement at the world body, but it represented a significant humiliation for Assad, whose government had sought to block the vote and severely criticized the sponsors, including Syria's brethren in the Arab League.

Bashar Jaafari, Syria's ambassador to the United Nations, called the resolution "biased" and said it had "nothing to do with events in Syria."

The resolution, which calls for Assad to relinquish powers to a vice president, negotiations among the antagonists and the formation of a new government, had been put forward by Egypt and other Arab League members. It followed the veto by Russia and China nearly two weeks ago of a resolution by the Security Council.

Syrian opposition groups reported an expansion of the military campaign Thursday.

The Local Coordination Committees, a Syrian activist group that has sought to document casualties and atrocities, reported that at least 63 people were killed Thursday, including at least four in Daraa. The group included in that total an account of what it said was a military massacre of 15 detainees in Jisr-Shougour, an area in northwestern Syria near the Lebanon border, along with five of their relatives who had sought to retrieve the corpses. These accounts could not be independently verified.

Earlier Thursday, hours before the General Assembly vote, Ban Ki-moon, the U.N. secretary-general, criticized Syria while on a visit to Vienna.

"On Syria, I continue to be gravely concerned at the level of violence and mounting loss of life," he said.

Referring to a bleak appraisal of the Syrian conflict made at the General Assembly earlier in the week by his top human rights official, Navi Pillay, Ban recited the statistics she had compiled: More than 5,400 Syrians killed, thousands missing, 25,000 refugees in other countries and more than 70,000 internally displaced.

"Every day those numbers rise," Ban said. "We see neighborhoods shelled indiscriminately. Hospitals used as torture centers. Children as young as 10 years old jailed and abused. We see almost certain crimes against humanity."

Rick Gladstone