The Northern Ireland Council for Ethnic Minorities said groups representing all three communities have received letters purportedly from the Ulster Young Militants. It is the youth wing of Northern Ireland's major Protestant paramilitary group, the Ulster Defense Association, and has a long track record of attacking outsiders who try to live in the most hard-line Protestant districts.

The letters warn the Polish, Indian and Muslim associations in Belfast to vacate their premises or "your building will be blown up." The threats end with the declaration, "Northern Ireland is only for white British."

Racism has been a growing problem over the past decade in Northern Ireland, where immigrants have arrived by the thousands following the territory's 1998 peace accord.

Most have settled in the lowest-rent parts of Belfast, which largely are impoverished Protestant districts with many empty properties.

Those areas are currently covered with the red, white and blue of the Union Jack _ with flags, overhead bunting and painted curbstones _ as the Protestants prepare to celebrate their major patriotic holiday, the "Twelfth," featuring massive nighttime bonfires over the weekend and parades across Northern Ireland on Monday.

The letters revealed Thursday tie their threats to the festivities, which commemorate the Protestant side's 17th-century military victories over the Irish Catholic minority. The holiday always heightens tensions that can turn violent.

"No sympathy for foreigners. Get out of our Queen's country before our bonfire night and parade day," the letter said.

This year's Twelfth buildup also features traditional Protestant-Catholic antagonisms. Five Catholic churches suffered damage from paint-filled balloons, graffiti and broken windows Thursday, while arsonists tried to burn down a Protestant community hall in north Belfast. All the buildings were unoccupied.

Last month the bulk of Belfast's Romanian Gypsy population was flown back to Romania at British taxpayer expense after street mobs intimidated some from their homes in Protestant areas.

In March, Protestant gangs waged running street fights with outnumbered Poles after a Northern Ireland-Poland football match in Belfast. Police also arrested four people Thursday on suspicion of beating to death a 40-year-old Polish man in the border city of Newry, although police have declined to say whether that killing had a racist motive.

Patrick Yu, executive director of the Northern Ireland Council for Ethnic Minorities, said he didn't think the Ulster Young Militants were serious in their threat to blow up buildings. He said the militants "just want to scare people" and discourage foreigners from feeling at home in Northern Ireland.