The U.S. Senate, concerned about a bird flu pandemic, has approved $8 billion to stockpile vaccines and other drugs to prepare for a potential outbreak of the disease.

The measure, contained in an amendment to a Health and Human Services spending bill, was approved on a voice vote.

Assistant Senate Democratic Leader Dick Durban, an Illinois Democrat, is a sponsor. "It might not be this winter, it might not be next winter, but it is going to happen. The virtual certainty of the pandemic flu is what public health officials are telling us that we as a country need to be prepared for."

The measure, which the House of Representatives has yet to approve, would also help hospitals expand their ability to handle a likely surge in patients, and increase global efforts to detect and contain a flu pandemic.

In a compromise, Democrats agreed with Senate Republicans to give the president flexibility, with input from Congress, in how the money would be spent. "The funds will be expended at the discretion of the President," said Senator Arlen Specter, a Pennsylvania Republican.

Bird flu, which is widespread among flocks of poultry in Asia, has spread west into parts of Europe. Scientists are concerned that the virus could mutate in a way that humans could easily pass it among themselves, which could result in millions of deaths.

Senator Durbin says the Bush administration has been slow to act on a plan to respond to bird flu. "Japan has had its national pandemic preparedness plan in place since 1997," he said. "Canada, Australia, Great Britain, all had a national preparedness plan in place. We look forward to seeing the plan from this administration."

Health and Human Services Secretary Michael Leavitt said in a Washington speech Thursday that the administration is close to announcing a plan to deal with a possible bird flu pandemic. He said the plan would include better disease reporting and the stockpiling of vaccines.