LONDON – British lawmakers on Friday criticised government spending of 424 million pounds ($702 million) to stockpile Roche's medicine Tamiflu, saying doubts about the drug's effectiveness suggest it may not be money well spent.

Parliament's influential Public Accounts Committee (PAC) said it was "surprised and concerned" to discover that information on methods and results of clinical trials of such prescribed drugs "is routinely withheld", and said there was a "lack of consensus over how well Tamiflu ... actually works".

"The case for stockpiling antiviral medicines at the current level is based on judgment rather than on evidence of their effectiveness during an influenza pandemic," said Richard Bacon, a leading member of the committee.

He added that as well as spending more than 420 million pounds on stockpiling Tamiflu, an antiviral medicine, the Department of Health was forced to write off 74 million pounds of that as a result of poor record-keeping by the National Health Service.

"Before spending money in future to maintain the stockpile the (health) department needs to review what level of coverage is appropriate," he said.

Tamiflu has been approved by regulators worldwide and is stockpiled by many governments in case of a global flu outbreak. Sales of the drug hit close to $3 billion in 2009, due to the H1N1 swine flu pandemic, although they have since declined.

But some researchers claim there is little evidence Tamiflu works and have lobbied since 2009 for Swiss drugmaker Roche to hand over all its data from clinical trials of the medicine.

After a lengthy fight, Roche agreed last year that it would hand over the data to outside researchers at the Cochrane Collaboration, a non-profit group that reviews trial data to assess the value of drugs.

The PAC said it was "extremely concerning that there has been a five-year delay and that there continues to be a lack of clarity" over whether medicines regulators and safety authorities had access to full trial results.

Beyond the Tamiflu situation, the committee said it was concerned that information on methods and results of clinical trials is routinely and legally withheld.

"This longstanding regulatory and cultural failure impacts on all of medicine, and undermines the ability of clinicians, researchers and patients to make informed decisions about which treatment is best," it said in its report.

The PAC report forms part of a wider debate about access to data from clinical trials conducted by the pharmaceutical industry to test the efficacy of and win marketing approval for new drugs. Critics say drugmakers routinely hide or bury trial data which is unfavourable.

Tracey Brown, director of a group called Sense About Science, which a year ago launched AllTrials - a campaign fighting for all data from all trials of all prescribed drugs to be made available - said the PAC report "adds to the clamour of voices" calling for more transparency in the drug industry.

"There is no excuse for not publishing results, but a huge public benefit to having a complete picture of what was found in trials conducted on treatments currently available to patients," she said.