Sam Allardyce believes that a swine flu outbreak at Stamford Bridge is likely after Blackburn Rovers’ game away to Chelsea on Saturday went ahead despite two of his players falling ill with the virus.

David Dunn and Christopher Samba are believed to be the pair who missed Blackburn’s 5-0 Barclays Premier League defeat. Since then a third, unnamed player who did take part is showing symptoms of the H1N1 virus. So are two of Rovers’ staff, including the club doctor.

Allardyce thinks that the virus could have been passed on to the Chelsea squad. “There is no doubt about that,” the Blackburn manager said. “When you look at the medical side of it, it is one of the most infectious viruses we have had. They are not going to stop it, are they?”

Chelsea are understood to be confident that their medical department has taken all the necessary precautions to protect the health of their players and staff.

Blackburn’s Carling Cup fourth-round tie against Peterborough United at Ewood Park will go ahead tonight after the Lancashire club confirmed that they will fulfil the fixture.

The Times has also learnt that Mikele Leigertwood, of Queens Park Rangers, returned to action against Derby County on Saturday after missing two matches with swine flu. It was caught early and Leigertwood was immediately isolated from the rest of the squad.

Allardyce criticised the Premier League for failing to take decisive action after Blackburn warned them of the outbreak before the game, yet admitted that the club had not asked for a postponement. He said that such a request would have been pointless.

“I would not have [commented] to the extent I have today, but reading in the paper that the Premier League said we made no request to get the game called off, that’s just sitting on the fence — normal splinters up the backside as usual,” he said.

“They know that we went through the right procedures and that we did not call it off because we couldn’t. There was no point [trying] because [last season] they told us we had to get a team out there no matter what.

“It is their responsibility to consider how dangerous it might be to allow this to spread throughout football, so they have shirked responsibility, not us. I don’t think they have put much thought into it at all.”

The Premier League said that it will consider postponement requests on a case-by-case basis. It is reluctant to call off matches except in extreme cases, taking the view that most clubs have squads large enough to cope with a couple of absences.

When ten Tottenham Hotspur players fell ill with a vomiting bug before a key game against West Ham United in 2006, the League refused Tottenham’s request to postpone it.

A spokesman said yesterday: “The Premier League does not anticipate at this stage a situation where any game will be postponed as a result of swine flu.

“Any postponement will have to be granted by the board of the Premier League and clubs would have to prove they couldn’t fulfil the fixture with the first-team squad available to them.

“The Premier League are telling clubs to seek and follow government advice when it comes to preventing or dealing with swine flu and take necessary precautions.”

Clubs are increasingly conscious of the threat. A spokesman for Stoke City said: “A couple of players had flu-like symptoms but they came through it. The players had their routine flu jabs a few weeks ago.” Aston Villa are “monitoring the situation on a daily basis”, while Portsmouth have installed anti-bacterial gels for hand-washing at Fratton Park and their training ground.

Micah Richards, the Manchester City defender, is believed to have become the first British footballer to catch the virus while on holiday in Cyprus in July. The next month, the Russian health ministry advised fans not to travel to their country’s World Cup qualifying match against Wales in Cardiff because they believed supporters would be at risk.

If the situation worsens over the winter and the Government recommends the suspension of public gatherings such as football matches, the sport’s authorities would have to decide whether to postpone fixtures or order them to be played behind closed doors, as happened in Mexico at the end of last season.

According to the NHS, there were 53,000 new cases last week, double the number in the previous seven days. So far, 122 people have died from the virus in the UK.

“I would not be too worried if I was a member of the Chelsea squad,” Dr Mark Porter, The Times’s doctor, said. “While it is theoretically possible for people to pass flu viruses on before they develop disabling symptoms, the window is very short and I doubt any Blackburn players would have been fit to play had they been contagious.

“Even if they were, swine flu requires close contact to spread easily and spending a couple of minutes in a tunnel and an hour and a half on a pitch in the fresh air hardly constitutes close contact. I have had families living under the same roof for days on end where only one member has gone down with the virus.”