The United States has sent a naval battle group to the Mediterranean off Turkey as a warning to Saddam Hussein not to interfere with U.S. troops building camps for Kurdish refugees in northern Iraq, the Navy said Tuesday.

Iraqi forces remained in the northern Iraqi city of Zakho, defying U.S. orders that they move away from the area where protected camps for Kurdish refugees are being built.Navy officers in Saudi Arabia said the aircraft carrier Theodore Roosevelt and the guided missile cruiser Richmond K. Turner, which were part of Operation Desert Storm, had moved from the Red Sea to bolster ships of the 6th Fleet off the coast of Turkey, close to northern Iraq.

The presence of Saddam's troops in northern Iraq could discourage Kurdish refugees from coming down from remote camps on the mountainous border with Turkey, where the State Department says about 510 refugees are dying daily.

As part of a stepped-up U.S. relief effort, American troops were arriving with more aid at the worst-off border refugee camps, at Cukurca and Uzumlu.

The Office of the U.N. High Commissioner for Refugees said Tuesday that a U.N. team would go to Iraq to launch an aid effort for any refugees returning from Turkey and Iran. The 10 to 15 relief experts would be the first such group to go to Iraq under terms of an aid agreement signed by the United Nations and Iraq last week.An estimated 850,000 Kurds from northern Iraq fled Saddam's forces to mountains along the Turkish border after a failed rebellion following the Persian Gulf war, and Turkey and the United States hope to persuade them to move to camps being set up under allied protection in northern Iraq.

An additional 1.5 million Kurds sought refuge in the mountains along the Iran-Iraq border. Shiite Muslims, who rebelled in southern Iraq, also fled into Iran, and Iran's official Islamic Republic News Agency said Tuesday that newly arrived refugees report that Shiite rebels continue to clash nightly with Saddam's troops in southern cities.

The United States said that Iran had agreed to accept American aid for Kurds in Iran and that U.S. planes might fly the supplies in. The two countries have not had diplomatic relations since 1979.

On Monday, an advance party of British Royal Marines arrived in northern Iraq to set up a headquarters for the relief operation, joining at least 2,000 U.S. troops setting up a refugee camp outside Zakho. A French contingent also has arrived.

Reporters who visited the camp outside Zakho said about 200 tents had been erected since Sunday and 400 more were being put up.

Reporters said about five Kurdish clan leaders inspected the camp Monday and appeared pleased.

In Washington, spokesman Richard Boucher said the United States estimated about 600 tons of supplies were required daily to meet the needs of the refugees. "As of today, we're over 400 tons a day, delivered primarily by air," he said.