BAGHDAD, Jan. 16 — The United Nations reported Tuesday that more than 34,000 Iraqis were killed in violence last year, a figure that represents the first comprehensive annual count of civilian deaths and a vivid measure of the failure the Iraqi government and American military to provide security.

Numbers of civilian deaths have become the central indicator for the trajectory of the war and are extremely sensitive for both Iraqi and American officials. Both track the tallies but neither will release them.

This latest figure was the first attempt at hand-counting individual deaths for an entire year. It was compiled using statistics from local morgues, hospitals and municipal authorities across Iraq and was nearly three times higher than an estimate for 2006 compiled from Iraqi ministry tallies by The Associated Press earlier this month.

An Iraqi government spokesman called the count exaggerated and said it had been obtained using “incorrect sources.” Though the Iraqi government closely tracks deaths through the Interior and Health Ministries, he said it did not have a system in place for compiling a comprehensive figure.