The tricky relationship between regulators and industry is thrown into the spotlight again as it emerges drugmakers paid hefty fees to attend meetings of a panel that advises the FDA.

An investigative report in the Washington Post found that pharma companies paid as much as $25,000 to attend sessions convened by a scientific panel on painkillers, and has led to claims that the industry was being given an opportunity to influence federal policy in this area.

The panel under scrutiny is the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT), which is attended (but not run) by the FDA and other regulatory authorities - including the EMA - and has been meeting since 2002.

The Post examined email correspondence obtained under freedom of information requests and found that FDA officials sat on steering committees and co-wrote papers with pharmaceutical industry employees.

Only industry representatives were asked to pay fees to attend, and the article suggests at least one federal official was nervous about attending meetings "paid for by a few large pharmaceutical firms who are assumed to be influencing the outcomes."

Ohio attorney Craig Mayton - who made the request for the emails and is cited in the report - criticises the FDA for participating in the meetings and says that "instead of protecting the public health, the FDA has been allowing the drug companies to pay for a seat at a small table where all the rules were written."

He also accuses the FDA of making "disastrous decisions" over the last 10 years in its handling of analgesic products.

The FDA said in a statement that it was taking the allegations seriously but was "unaware of any improprieties" associated with IMMPACT, an initiative set up by Robert Dworkin of the University of Rochester and Dennis Turk of the University of Washington.

Dworkin told the Post that the scientific guidelines produced by IMMPACT - designed to improve the testing standards for new painkillers - were of high quality. The organisation's website is sponsored by 11 pharma companies, including Pfizer, Johnson & Johnson, Eli Lilly, Astellas and Purdue Pharma.

The FDA's deputy director Douglas Throckmorton said that the group was not set up and run by the agency so did not have to operate in accordance with federal rules on transparency and funding.