Polish authorities have abandoned hope of finding survivors in the wreckage of a trade centre, where at least 66 people died and 160 others were injured after the roof collapsed.

Police called off the rescue effort at 5 a.m. local time Sunday, about 12 hours after the roof fell on about 500 people at a racing-pigeon exhibition in the southern city of Katowice.

Katowice Police Chief Kazimierz Krzowski said no survivors had been found for more than six hours.

Rescuers try to lift a collapsed roof in Katowice, southern Poland, Saturday, Jan. 28, 2006. The roof collapsed on an international pigeon fair, with hundreds inside. (AP photo)

"We are bringing out corpses," Krzowski told the Associated Press.

Nearly 1,000 police officers, firefighters, soldiers and volunteers used police dogs and heavy equipment to search the twisted metal and broken beams all night. They also blew warm air into the wreckage in a bid to keep survivors alive as the temperature dropped to –17 C.

Krzowski promised the search teams would "work till the end" to recover the bodies of the victims in the 10,000-square-metre hall.

Earlier, witnesses had said some of the trapped people had been using cellphones to call family members or emergency services.

The dead and injured included foreigners and children, officials said.

The exhibition had drawn pigeon racing fans from across the continent. Hospital officials said the injured included Germans, a Czech and a Belgian as well as Poles.

The Polish prime minister promised an inquiry to find out why the roof of the 10,000-square-metre hall caved in.

Early reports suggested a heavy snow load might have caused the collapse.

Much of eastern and central Europe has been coping with heavy snowfall and severe cold for much of the winter.

In early January, 15 people died when snow caused the roof of an ice rink to collapse in the town of Bad Reichenhall in southern Germany.