Iraqi forces hammered at Kurdish rebels Friday in their mountain bulwarks, and a rebel chief begged for more aid for hundreds of thousands of the starving, shivering refugees.

The U.S. military announced it was deploying 3,500 additional troops with ships and 50 helicopters to boost its relief efforts for the refugees fleeing Saddam Hussein's forces in Iraq."These forces will continue the rapid expansion of the largest U.S. relief effort mounted in modern military history," said a statement from headquarters of the U.S. European Command in Frankfurt, Germany.

Defense Secretary Richard Cheney said earlier that the Bush administration had no intention of sending combat troops to northern Iraq to aid the refugees. Asked whether non-combat units might be sent in, he said, "At this point, we've not made that decision."

Britain's foreign secretary, Douglas Hurd, hinted Friday in London that the allies could use force again if Iraq interferes with Western efforts to help the refugees.

"We and our allies are preparing contingency plans to respond firmly to any . . . use of force" against relief workers, Hurd said. "Iraqi action cannot be allowed to impede humanitarian relief."

The United States also was moving ahead with plans to repatriate its military from southern Iraq and elsewhere in the gulf region. The Marines, who harnessed nearly their entire strength for the gulf war, said they should almost all be home before May.

Austrian Maj. Gen. Gunther Greindl, commanding general of the U.N. peacekeeping force, was to fly to Kuwaitfrom Jordan today at the head of an advance unit that will begin replacing U.S. troops along the Iraq-Kuwait border.

In northern Iraq, resistance leader Massoud Barzani said the army attacked in strength north of the city of Suleimaniyah at dawn Friday, after another heavy thrust Thursday north of Sulahedin, which is northeast of Suleimaniyah.

Barzani said the army also seized the nearby city of Azmar, but withdrew with heavy losses when the rebels counterattacked.

Barzani said government military action against the Peshmerga, as the rebels are called, has not diminished despite repeated U.S. warnings to the Iraqi leader to stop attacking refugees in a zone above the 36th parallel. The White House said Friday it had no reports of such Iraqi attacks.

Rebel spokesmen outside Iraq said the government continues to use -heli-copter gunships, but Associated Press correspondent Alex Efty, with Barzani at his headquarters, saw none in use.

Barzani said the situation of the fleeing Kurdish refugees is getting more desperate.

The official Iraqi News Agency, monitored in Nicosia, said tens of thousands of Kurds were coming out of the mountains to accept government offers of amnesty.

INA also challenged a statement made Wednesday by Iran that 22 aircraft were flown to Iran for safekeeping during the gulf war and would be returned.

It quoted Iraqi Foreign Minister Ahmad Hussein as saying a total of 115 military and 33 civilian planes were flown to Iran. The 148 total was slightly higher than earlier allied reports of 137 aircraft moved to get them out of the way of allied bombing.

Advance elements of the U.N. peacekeeping force are expected to arrive in Kuwait today, a day later than planned, because they could not get clearance to land in Kuwait. Officials at the United Nations said the delay was caused by technical problems having to do with Kuwait's damaged communication systems.

Greindl and other senior officers are due to go to Baghdad on Sunday.

Once they have talked to both governments, their troops should start taking over U.S. positions along the 150-mile border.

In northern Iraq, conditions for the Kurdish refugees deteriorated despite international efforts to get them aid.

Barzani reported, "No foreign relief aid has reached tens of thousands in the northeastern corner of Kurdistan right on the Turkish border waiting to cross."

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Persian Gulf wrap-up

- The last of the U.S. Marines who helped allied forces drive Iraq from Kuwait are nearing the end of their stay. Military officials said that with a formal gulf war cease-fire in effect they expect the remaining 29,000 Marines in the theater to be home by the end of April.

- The five permanent members of the U.N. Security Council met Friday to consider a British initiative to create safe haven zones in Iraq to protect Kurds and Shiite Muslims, but no action was expected soon.

- Aid bundles dropped by Western planes crushed and killed four Iraqi refugees Friday near the Turkish border. It was the second such accident since widespread relief efforts began this week.