The US has imposed economic sanctions on Yugoslavia and is working with NATO on possible military action to end the conflict in Kosovo. But the use of US ground troops is unlikely.
Officials in Washington said that if military action was authorised to end attacks by Serbian troops on Kosovo, air power was likely to be used.
There was some confusion over the US attitude towards military action when President Clinton's national security adviser, Mr Sandy Berger, said a US military intervention was "not something that is on the table".
Later, other officials said Mr Berger was simply describing US expectations in the short term and was not ruling out military options if economic sanctions did not work. What Mr Berger meant was that unilateral US action was not being considered and that planning was being left to NATO.
The State Department spokesman, Mr James Rubin, said that the US was working closely with allies and partners on measures to end the violence in Kosovo and promote a peaceful resolution.
"This includes accelerated contingency planning in NATO," he said. The US decision to ban American investment in Yugoslavia and freeze that country's assets in the US follows similar action by EU foreign ministers. The US had asked for the sanctions to be suspended last month to allow for talks between President Milosevic and Mr Ibrahim Rugova, leader of the Kosovan Albanians. But since then, increased fighting has caused at least 250 deaths and led to the flight of 10,000 ethnic Albanians from Kosovo.
Agencies report:
The German Chancellor, Dr Helmut Kohl, said yesterday that President Yeltsin had offered to use his influence with the Yugoslav government to help resolve the conflict in Kosovo.
Mr Yeltsin's spokesman, Mr Sergei Yastrzhembsky, said a meeting between the Russian leader and President Slobodan Milosevic of Yugoslavia in the near future was quite possible.
In Geneva, the UN refugee agency and UNICEF demanded action from the international community to stop the bloodshed. "The UNHCR is feeling a sense of deja vu with what is happening in Kosovo [recalling Bosnia in the 1990s] and we hope that vigorous action will be taken to put a stop to the fighting," said Ms Judith Kumin.
The UNICEF spokesman, Mr Patrick McCormick, said the agency supported any options which would save the lives of civilians, especially women and children.
The UN High Commissioner for Human Rights, Mrs Mary Robinson, said she was "deeply disturbed" by the fighting. She cited reports of 37 people killed in the last four days of May and more than 130 in the area around Decani and Djakovica, near the Albanian border.
Albanian sources say 300 people, mostly ethnic Albanians, have been killed since the Serbs began a new offensive to crack down on an underground separatist movement at the end of last month.
Daily reports of human rights violations, including arbitrary killings and shellings of villages, were mounting, Mrs Robinson said. "I am concerned that this violence is taking place in a region where approximately 47 per cent of the population is under the age of 18," she said.
In Belgrade yesterday, President Milosevic held a meeting of the Supreme Defence Council on Tuesday in the presence of the Serbian and Montenegrin presidents to discuss the Kosovo crisis.