The Health Protection Agency has confirmed a further 29 cases of swine flu in England bringing the total number of UK cases to 621.
Of the new cases, 23 are in the West Midlands, four in the South East and two in the North West.
As well as 426 confirmed cases in England there have been 189 people in Scotland diagnosed with the virus, four in Northern Ireland and two in Wales.
However, there are also a further 523 possible cases under investigation.
The news of more cases comes after leading scientist Professor Hugh Pennington, a bacteriologist at Aberdeen University, warned that the number of people with the illness could be twice as many as the official total.
So far the World Health Organisation has had reports of more than 25,000 cases of swine flu in 73 countries and at least 139 have died from swine flu, a majority in the US and Mexico.
A Department of Health spokesman said: "The localised cases of swine flu found in the UK have, in the majority of cases, not been severe and we have not seen evidence of widespread community transmission.
"But we must not be complacent, it is right to prepare for the possibility of a global pandemic."