US army and air force reserves are to be called up, President Clinton said yesterday, because the NATO attacks on Kosovo were moving to "the next level".
The President will also ask Congress to approve an emergency supplementary budget to fund the US effort. The extra cost for the American taxpayers could reach $8 billion this year, according to some members of Congress.
Reservists called up will be used for various tasks such as piloting air tankers and acting as liaison with the populations in Albania and Macedonia.
Mr Clinton is expected to approve a request from the NATO commander, Gen Wesley Clark, for about 300 more US warplanes which would bring the number to 800. But there are conflicting signals about whether Mr Clinton is considering sending ground troops into Kosovo.
The White House spokesman, Mr Joe Lockhart, insisted that the President "has no intention of introducing ground troops into a hostile environment", but several members of Congress left a meeting with Mr Clinton yesterday saying that the ground troops option has not been ruled out.
A Democratic Senator, Mr John Kerry of Massachusetts, told reporters that he heard Mr Clinton say that "he does not personally believe at this time that they [ground troops] will be necessary to achieve the goal. But I also heard him say that he believes nothing is essentially off the table."
Later Mr Clinton made one of his strongest statements on the situation, declaring: "Our campaign is diminishing and grinding down Mr Milosevic's military capabilities. We have reduced his ability to move, sustain and supply the war machine.
"We have damaged his refineries and diminished his capacity to produce ammunition. We are striking now at his tanks and at his artillery and have destroyed more than half his advanced MiG 29s. Now we are taking our allied campaign to the next level."
Mr Clinton said that the humanitarian effort for the refugees who have fled Kosovo was also being stepped up. He said that the plight of thousands of refugees inside Kosovo was "a huge problem".
Using air drops of food and supplies would mean that Serb forces could seize them and also put allied aircraft at risk. "It is a huge problem and we are working very hard at it," he said.
President Milosevic could "end this crisis right now," Mr Clinton said. He could do this by withdrawing his forces from Kosovo, permitting the deployment of an international security force and allowing the return of all displaced persons.
Mr Clinton's series of meetings with members of Congress has had the effect of rallying support behind the NATO air strikes and of putting off calls for an immediate debate to authorise ground forces.
"I think it's too early to have that debate," the Speaker of the House of Representatives, Mr Dennis Hastert, said after a meeting at the White House with Mr Clinton.
The Senate majority leader, Senator Trent Lott, said that it was not helpful for members to be pressing for a debate on ground troops but "I don't think we should preclude anything . . . I think we need to see how this thing progresses."
Agencies add:
Gen Clark apologised yesterday for the bomb which killed an estimated 10 train passengers when a bridge south of Belgrade was targeted and blown up. It was "an unfortunate incident" which everyone regretted, he said.
The attack had been remotely directed from many miles away and the pilot only saw movement on the bridge at the last moment through his target screen. Gen Clark said: "As he stared intently at the desired aim point on the bridge, all of a sudden, with less than a second to go, he caught a flash of movement that came into the screen.
"It was the train coming. Unfortunately he couldn't dump the bomb. It was locked, it was going into the target. It was an unfortunate incident which he and the crew and all of us very much regret."
But Gen Clark made it clear that the error had not weakened NATO's resolve to see the conflict through. He said: "We are going to do everything we can to continue to work the air campaign in an effective manner that avoids needless damage and collateral damage and achieves the objectives set out in this campaign."
Meanwhile, the Serb army was accused yesterday of using gang rape as a key part of its campaign of ethnic cleansing in Kosovo.
Reports were emerging of women being separated from refugee columns to be raped by soldiers while their families were either forced to watch or driven away at gunpoint.
The British Foreign Secretary, Mr Robin Cook, told a news conference in London that victims were forced to endure "systematic rape" in an army camp at Djakovica near the Albanian border.
Just before a group of refugees entered Albania, Serb soldiers singled out an attractive 22-year-old woman from the rest of her family and indicated they should go on without her, according to UN refugee agency officers.
Fearing she would be abducted or raped, her family argued with the soldiers and in the confusion the young woman reportedly made a run for one of the departing tractors.
She was then allegedly shot dead by a Serb soldier, according to reports from several witnesses.