Gordon Brown makes the announcement at Prime Minister's Questions.

Three further cases of swine flu were confirmed in Britain by Gordon Brown today  – including an adult in Birmingham.

The other two cases are of a 12-year-old girl from Torbay and an adult from London.

The Prime Minister said all three had recently travelled from Mexico, had “mild” symptoms and were responding well to treatment.

The girl’s school has been temporarily closed and all other pupils offered anti-viral drugs.

Mr Brown told the Commons: “I believe that we are taking the preparations that are necessary and the precautions to prevent the incidents of this disease in this country.

“I can confirm that we have enhanced airport checks, I can also confirm that we are advising people not to travel to Mexico unless necessary. We will continue to review that position.”

He said by Tuesday next week, an information leaflet would be available for every family in the country, and that anti-viral stocks had been expanded from 35 million to 50 million, plus extra face masks ordered.

“The World Health Organisation has said we are one of the best prepared countries,” said Mr Brown.

“We intend to keep it that way, and intend to do everything in our power to make sure people are safe from this worldwide flu,” he added.

The first British victims were revealed to be newlyweds Iain and Dawn Askham from Polmont, near Falkirk in the Scotland, who are now recovering in a Lanarkshire hospital.