Barack Obama has declared the swine flu outbreak a national emergency in the US

US President Barack Obama has declared the swine flu outbreak a national emergency and empowered his health secretary to suspend federal requirements and speed treatment for thousands of infected people.

The declaration authorises Health and Human Services Secretary Kathleen Sebelius to bypass federal rules so health officials can respond more quickly to the outbreak, which has killed more than 1,000 people in the United States.

The goal is to remove bureaucratic roadblocks and make it easier for sick people to seek treatment and medical providers to provide it immediately.

That could mean fewer hurdles involving government-funded health insurance programs for the poor and elderly or health privacy regulations.

"As a nation, we have prepared at all levels of government, and as individuals and communities, taking unprecedented steps to counter the emerging pandemic," Mr Obama wrote in the declaration.

He said the pandemic keeps evolving, the rates of illness are rising rapidly in many areas and there's a potential "to overburden health care resources".

Because of vaccine production delays, the government has backed off initial, optimistic estimates that as many as 120 million doses would be available by mid-October. As of Wednesday, only 11 million doses had been shipped to health departments, doctor's offices and other providers, according to the federal Centres for Disease Control and Prevention.

The government now hopes to have about 50 million doses of swine flu vaccine out by mid-November and 150 million in December.

The flu virus has to be grown in chicken eggs, and the yield hasn't been as high as was initially hoped, officials explained.

Swine flu is more widespread now than it's ever been. Health authorities say almost 100 children have died from the flu, known as H1N1, and 46 states now have widespread flu activity.