A U.N. weapons team worked through the night on an inspection that included visits to two sites Iraq considers sensitive, a U.N. official said Monday.

The team was led by American inspector Scott Ritter, whom Iraq once barred from working in the country. His visit is considered a test of Iraq's willingness to adhere to a deal brokered by U.N. Secretary-General Kofi Annan to end a standoff over the inspections.Alan Dacey, spokesman for the U.N. Special Commission that oversees the inspections, said Ritter's team left U.N. headquarters in Baghdad at 9 a.m. Sunday and didn't return until 5:20 a.m. Monday.

Dacey did not say exactly where Ritter was working or what types of weapons he was searching for, but said, "They did a number of sites, two of which were sensitive."

"All sites were inspected to the satisfaction of the team," Dacey said.

Sensitive sites include ministries and headquarters of intelligence or military operations. Special procedures are followed in inspecting such sites, with the U.N. teams generally accompanied by high-ranking Iraqi officials.

Under the deal with Annan, Iraq committed itself to full cooperation with the inspections. It also pledged to open eight presidential compounds to a special committee that will include U.N. diplomats and inspectors.

Iraq had said the palaces were off-limits on grounds of sovereignty, and the United States had threatened a military strike to force Baghdad to relent.

Ritter's more than 20-hour inspection overnight Sunday was the longest conducted by his 50-member team since arriving last week.

The team inspected six sensitive sites on Friday and Saturday, Dacey said. An Iraqi sources said that one of the locations visited Friday was a barracks of the elite Republican Guard.