Federal health regulators lack the resources necessary to track the safety of new drugs and respond quickly to any problems that might crop up, a panel of experts said Friday.

Problems in Food and Drug Administration oversight were highlighted when the popular painkiller Vioxx was pulled from the market in 2005, six years after its approval, after long-term use was linked to an increased risk of heart attack and stroke.

"FDA's performance in approving drugs or monitoring their safety after approval has been questioned and criticized," the Institute of Medicine panel said.

The institute said there was an appearance of a crisis in drug safety but did not make a determination of whether one actually exists.

"More drugs are being approved faster with less time to intensively investigate premarketing safety data," the report said. But FDA does not have the resources to keep up once the drugs reach the market in assessing safety or informing the public about any risks that might develop.

The experts acknowledged that the agency and others in the drug industry had taken some steps to try to improve drug safety but that they were not "equal to the task. Major obstacles remain."

The panel proposed a series of steps to improve safety review, including boosting FDA's budget, whether through an appropriation from Congress or taxes.

It also recommended the FDA review the safety of all new drugs five years after their introduction -- making their initial approval almost tentative and subject to withdrawal. New drugs also would carry a symbol for two years alerting patients and doctors that uncertainties may remain about their risks and benefits. Advertising would be restricted during that two-year period, according to the report.

The Institute of Medicine advises the government on health policy. The FDA partially sponsored the report.