BAGHDAD, Iraq (AP) _ In the first test of a U.N. agreement forged to avert a military strike against Iraq, weapons inspectors spent eight hours Thursday going over parts of a presidential estate previously declared off-limits.

One diplomat, Horst Holthoff of Germany, described Iraqi cooperation as ``fantastic, absolutely positive.''

``I am personally really impressed by the spirit of cooperation. The team saw everything (it) wanted to see,'' Holthoff said, without elaborating.

Accompanied by diplomats from 20 countries, U.N. arms inspectors visited President Saddam Hussein's Radwaniyah Palace, a 9.3-square-mile complex of at least a dozen villas, five artificial lakes, and streets lined with palm trees.

The palace is the second-largest of eight presidential sites from which Iraq previously had barred inspectors, claiming them to be symbols of national sovereignty. Saddam once used it to host dignitaries.

Thursday's visit was the first test of the Feb. 23 agreement that Iraq signed with U.N. Secretary-General Kofi Annan, pledging to open the sites. The agreement averted the threat of military strikes by the United States and Britain.

``It's an important mission in implementing the agreement ... (an) extremely important mission for the international community,'' Saeed Sad, a Sudanese diplomat, said before leaving for Radwaniyah.

Cui Tiankai, China's representative, said ``we had a very good start to our work. ... It was interesting.''

U.N. spokeswoman Janet Sullivan said the officials completed inspections at two locations in the Radwaniyah area.

``It was a survey mission,'' she said. ``This process ... will continue until the baseline surveys are complete.'' She refused to elaborate.

A U.N. spokesman in New York said Radwaniyah is divided into three parts. Reporters were not allowed near the site, which is located near Baghdad's international airport.

Diplomats and U.N. officials refused to say how many inspectors were involved in Thursday's visit or what they were looking for.

In general, the inspectors are looking for documents and other evidence that weapons of mass destruction were made or stored at the palaces.

Until the inspectors certify that Iraq is rid of all its weapons of mass destruction, the U.N. Security Council will not lift economic sanctions imposed after Iraq's 1990 invasion of Kuwait.

Under the U.N. agreement, the weapons inspectors must be accompanied by the diplomatic observers, who will not participate in the searches but are there to ensure Iraq's national dignity. Iraqi Oil Minister Amer Mohammed Rashid and other senior officials also accompanied the inspectors.

The 20 diplomats, dressed in suits, did not talk to reporters as they headed off on their mission. Inspectors were dressed casually in pants, T-shirts and blue U.N. baseball caps.

The team of 58 inspectors is headed by American Charles Duelfer, who participated in the search Thursday.

Radwaniyah is one of the sites over which the dispute between the United Nations and Iraq first developed. American weapons inspector Scott Ritter was barred from entering the palace in 1996.

In December, Iraqi authorities took foreign reporters to Radwaniyah, in an attempt to prove that the compound contained no weapons.

It was not clear when other palaces would be inspected or what the experts expected to find given that the Iraqis have known about the searches since last month and could have removed incriminating evidence if any existed.

Chief weapons inspector Richard Butler has said the first inspections of the palaces will be of a ``baseline'' nature, laying the groundwork for more detailed searches later if necessary.

Butler said Tuesday that the palace inspections would last about two weeks, and he did not rule out future visits.

The total area of the eight palace compounds is about 12 1/2 square miles, and comprises 1,058 buildings.

Iraq has long insisted it has met all the requirements of the U.N. resolutions that imposed the sanctions, which include a ban on the unlimited export of oil, the country's most valuable commodity.

While U.S. officials have said that Saddam has dozens of palaces, the U.N. inspectors are primarily interested in the large presidential compounds. Iraq has never said publicly how many presidential palaces there are.

Some of the palaces serve as residences for Saddam and his family, while others contain guest houses for visiting dignitaries.