Three thousand arrived in Blace, the main crossing point on the border with Kosovo. More than 12,000 Albanians have crossed into Macedonia since the end of last week and the United Nations believes almost 150,000 more will come.
"We are now jammed to breaking point," said Ron Redmond, spokesman for the UN High Commissioner for Refugees (UNHCR) in Macedonia, after bus and train loads flocked to the already full Radusa camp near the capital, Skopje, yesterday.
A number of refugees had reported Serb atrocities, aid workers said, including one report that 16 people had been massacred at a village called Slavi last week.
Large numbers of people were reported to be waiting at railway stations along the Pristina-Blace route. Stations and bus stops were crowded and yesterday's train was too full to stop at Urosevac, between Pristina and the border.
Many of the 3,000 people who streamed into Blace on Monday were still waiting to be registered yesterday.
A new camp at Cegrane in western Macedonia for up to 20,000 people will not be ready to take refugees until later in the week.
Mr Redmond predicted that people would soon have to sleep in the open under plastic sheeting because there are not enough tents to accommodate them.
Macedonia's Foreign Minister, Aleksandar Dimitrov, said his country could not cope with the latest influx and would certainly not be able to assist 150,000 more. The Macedonian government has been reluctant to designate new areas for refugees camps, fearing the refugees may become permanent residents and tilt the ethnic balance between Slavs and Muslims.
Reports of a further big wave of refugees were echoed by the UNHCR. "We have received very credible reports suggesting that 150,000 more people are on their way out of Kosovo," said Lyndall Sachs of the UNHCR in London. "These are the numbers we are now making contingency plans to deal with."
Rachel Reilly, a Human Rights Watch researcher in Skopje, said there were worries about overcrowding in the camps. "The two biggest transit camps are completely crammed. You can hardly walk between the tents. Sanitation is almost non-existent."
She said there were grave concerns that Macedonia, which has taken in a total of 175,000 refugees since air strikes began, would close the borders, trapping tens of thousands of people at the border. This would violate its commitment to take in refugees under the Geneva Convention, she said. Another worry is the unreasonable restrictions on the freedom of movement of refugees inside camps, and the alleged harassment of Albanians by the Macedonian police.
She said aid supplies were still pouring into Macedonia but the country did not have the infrastructure for accommodating such vast numbers of people. "There is no long-term planning. This situation is just not sustainable."
Macedonia has sent about 26,000 refugees to third countries but airlifting refugees out of the Balkans is controversial and the red tape is slow. "We don't like this policy," said Lyndall Sachs, "but we have to do it." Britain and Spain took their first refugees on Sunday, while others have recently been sent to Austria, France, the Netherlands and Turkey.
Three planeloads left on Monday carrying 149 refugees to the Netherlands, 155 to Sweden, 134 to France, 147 to Finland and about 250 to Turkey. The refugee agencies are aware, however, that the public sympathy shown to displaced Kosovars in western Europe could turn sour. "We have had letters from people in Britain saying that they want the Government to take in refugees but not asylum-seekers."
More than 365,000 people have fled from Kosovo into Albania which is still operating an open-door policy. But the UNHCR has warned that Albania also desperately needs more international assistance.
More than 1,000 Kosovo refugees arrived on the coast of southern Italy yesterday, prompting concern that a much-touted flood of refugees was about to become a reality. A tourist boat normally used for river cruises arrived in Bari from Montenegro carrying 234 Kosovars, including 70 children, four of them newborn babies.
Other, smaller groups were found huddling on the beaches between Brindisi and Lecce or wandering in the countryside. The police said 1,385 people arrived between midnight and noon yesterday. The vast majority of the new arrivals are from Kosovo, though they include Kurds and people from Albania.