Britain could have more than 100,000 cases of swine flu a day by the end of August if the current rate of infection is maintained, Health Secretary Andy Burnham said.
"Cases are doubling every week, and on this trend we could see over 100,000 cases a day by the end of August, but I stress this is only a projection," Burnham told the House of Commons, the lower house of parliament.
He said Britain now had nearly 7,500 cases of swine flu and was moving into a new "treatment phase" as hundreds of new cases were confirmed every day.
Antiviral drugs would be offered to all those who have contracted the illness with higher-risk patients given priority, Burnham said.
Health officials have said Britain is abandoning a policy of trying to stop the flu spreading and instead focusing on patients most susceptible to it, such as obese people or those suffering from asthma or breathing problems.
The three people who have died in Britain after contracting swine flu all had "underlying health problems".