A survey by Barclaycard revealed that as many as six million workers are ready to call in sick, rather than risk missing England matches.

But the mass outbreak of football fever could cost the economy billions of pounds, especially if England do well.

The survey sought opinions from more than 4,000 football fans, and 40% of them admitted they would be happy to call in sick if their working hours clashed with England matches.

If that percentage is repeated among the estimated 15 million workers who want to watch England play, the cost to the economy if England were to reach the World Cup final could be as high as �3.2bn.

Even if England fail to get past the group stages, the loss is likely to exceed �1 billion.

Barclaycard sponsorship director Nic Gault said: "This research demonstrates the passion of football fans in the UK.

"I'm sure many of them would argue that if England win the World Cup it will all be worth it."

England's opening game against Sweden takes place on Sunday 2 June at 1030BST and is unlikely to have a dramatic effect on the workforce.

Massive audience

But their second match - against Argentina - kicks off at 1230BST on Friday 7 June, and is certain to attract a massive audience.

The third game against Nigeria starts at 0730BST on Wednesday 12 June and could attract as many viewers as the Argentina match if England are in with a chance of qualifying.

Subsequent games will have either early morning or lunchtime kick-offs.

A Barclaycard spokesman said one way to tackle the problem would be for employers to provide coverage of the matches for their staff.

"A huge number of our staff are football fans so we will be ensuring that they will be able to keep up to speed with all the Word Cup action by bringing in TVs," he said.