Several women hockey players were poisoned by carbon monoxide at the Kladno hockey stadium, with eight taken to hospital and three in intensive care unit, City Hall spokesman Ladislav Pavlik said on Saturday.

The gas probably came from the Zamboni, which is used to clear the ice surface, Pavlik said, adding firefighters have confirmed this suspicion, and the stadium has been closed after the incident.

Pavlik discribed the women' condition as "serious nausea."

"The Zamboni is not in ideal condition, which is why we recently decided to buy a new one," Pavlik said.

A spokesman for the firefighters said that the carbon monoxide came from imperfect combustion in the Zamboni's motor.

The women, who had been ill in recent days, were competing in a tournament also featuring Canada, Russia, Slovakia and the United States.

"Carbon monoxide is heavy and holds low to the ice. Unfortunately, it effects women more seriously than men," Pavlik said.

"Their lives are not in immediate danger and we don't expect them to have any permanent damage," a Kladno hospital doctor said.