FIFA has approved a research to determine whether the thrill of the World Cup can be literally heart stopping.

Previous research during international soccer tournaments has found an increase in the general incidence of heart attacks, particularly on days when tense matches have fans on the edge of their seats.

In the new FIFA-approved study researchers will receive blood samples from heart attack victims from all over Germany who were watching football at the time of the attack.

"Patients are asked precisely what they were doing at the time of the attack whether they were following football on the radio or television, or even watching the pundits after the game," David Leistner of Munich's Ludwig Maximilians University was quoted in reports.

Researchers plan to search the samples for traces of stress hormones which can clot the blood.

Doctors will also receive samples from anyone who collapses in a stadium during a World Cup match to check whether their blood has higher levels of hormones than fans watching at home.

"So far, on the days when Germany has played we have received a lot more blood samples," Leistner added.

A study in 1998 found the number of heart attacks increased by 25 per cent on the day and in the two days after England lost to Argentina in a World Cup penalty shoot-out.

Researchers in Switzerland also found heart attacks in the country increased by 60 per cent during the 2002 World Cup in Japan and South Korea even though the Swiss team was not competing.

The findings prompted calls for emergency heart attack equipment to be installed in stadiums during Euro 2004.

The study's first results are due in October.

"If it really is the case that higher stress levels increase the chance of a heart attack then attending soccer games may have to carry a health warning," said Leistner.