Outside experts with more than $50,000 in ties to drug and medical device companies regulated by the Food and Drug Administration would be barred from advising the agency under draft guidelines issued Wednesday.

The conflict-of-interest guidelines would allow scientific experts who accept less than $50,000 in corporate grants, contracts and consulting fees — or hold less than that amount in company stock — to still serve on the FDA's advisory committees. But that could happen only if the need for their services outweighed the potential conflict, and only if they were nonvoting members, according to the draft.

The agency relies on its panels of outside experts for recommendations on drugs, vaccines and devices. It wasn't immediately clear how many advisers would be barred, but Randall Lutter, the FDA's acting deputy commissioner for policy, told reporters it was a "significant number."

The release of the guidelines brought rare praise from a lawmaker and a watchdog who have criticized the FDA over the potential for conflicts of interest on its advisory committees.

"It represents a complete change in perspective and a completely renewed awareness of responsibility within the Food and Drug Administration," said Rep. Maurice Hinchey, D-N.Y., who has proposed FDA-specific legislation on conflicts of interest.

The FDA routinely grants waivers for outside experts that allow them to serve as advisers, even when they report financial ties, sometimes in the tens of thousands of dollars, that create the potential for a conflict of interest. The new guidelines wouldn't bar someone from serving on a panel, but could keep the person from participating in specific meetings about products where that person has a potential conflict.

Lutter said the FDA was unaware of any instances where the decision-making process was unfairly or inappropriately influenced in an adverse way by any conflicts its advisers had.

A recent study found that more than one-fourth of the experts relied on by the FDA for advice on drugs, including whether to approve new pharmaceuticals, reported a financial conflict.

The lead author of that 2006 Journal of the American Medical Association study, Dr. Peter Lurie, of the watchdog group Public Citizen, called the guidelines a significant advance. Lurie said that's in part because they will motivate the FDA to find prospective advisers who are entirely free of conflicts, lest the agency be left without a quorum at future meetings.

The FDA had long maintained that it would be impossible to exclude all advisers with industry ties since it would effectively deny the agency access to people with the expertise and experience it seeks. Hinchey and others have said that's untrue.

The guidelines also would limit the participation of experts at specific meetings if they had held a generally disqualifying financial interest within the preceding year.

The guidelines propose allowing the FDA commissioner to grant waivers that would allow otherwise disqualified advisers to serve. Lutter said such waivers would be rare.