It costs $8,000 (£5,000) a month and is given to about 17,500 women in the US a year. The drug was initially approved after a study found that, by preventing blood flow to tumours, it extended the amount of time until the disease worsened by more than five months. However, two new studies have shown that the drug may not even extend life by an extra month.

The FDA advisory panel has now voted 12-1 to drop the endorsement for breast cancer treatment. The panel unusually cited "effectiveness" grounds for the decision. But it has been claimed that "cost effectiveness" was the real reason ahead of reforms in which the government will extend health insurance to the poorest.

If the approval of the drug is revoked then US insurers would be likely to stop paying for Avastin.

The Avastin recommendation led to revived allegations that President Barack Obama’s overhaul of the US health care system would mean many would be denied treatments currently available.

During the debate, those opposed to the reforms cited Britain’s National Institute for Clinical Excellence, which decides whether new treatments should be made available on the NHS on the basis of cost effectiveness, as an example of the sort of drug rationing that amounted to a "death panel".

David Vitter, the Republican Senator for Louisiana, said the FDA decision amounted to rationing health care.

"I shudder at the thought of a government panel assigning a value to a day of a person’s life," he said. "It is sickening to think that care would be withheld from a patient simply because their life is not deemed valuable enough.

"I fear this is the beginning of a slippery slope leading to more and more rationing under the government takeover of health care that is being forced on the American people."

Avastin has been described as "the poster child for expensive anti-cancer drugs".

When reviewing drugs for approval the FDA is only charged with looking at their health risks and benefits, not cost effectiveness. It usually follows advisory panel recommendations. A final decision will be announced on Sept 17.

Avastin made $5.9 billion (£3.8 billion) in sales last year and is made by Genentech, a San Francisco-based unit of the Swiss drug maker Roche.

It is also approved for colon, lung, kidney and brain cancer, however, the FDA review and recommendation applies only to breast cancer.

An FDA spokeswoman said: "Avastin should be an option for patients with this incurable disease."

Breast cancer is the second most common cause of cancer death among US women, with 40,000 last year.

In the UK the National Institute for Clinical Excellence is reviewing whether Avastin should be available on the NHS for woman with breast cancer that has spread.

A spokeswoman said: "We will continue to investigate the treatment regardless of the FDA decision."