An independent review of NHS breast screening is under way after researchers suggested the harms may outweigh the benefits.

Professor Sir Mike Richards, national cancer director at the Department of Health, has initiated an independent review of research evidence after an argument arose among academics over the worth of mammograms.

Last month, researchers from the Nordic Cochrane Centre in Denmark claimed women undergoing NHS breast cancer screening are being "misinformed" and are not told about the harms of over-diagnosis. They said the harms of breast screening may outweigh the benefits and that screening information should be more balanced.

In an open letter to Sir Mike, published in the British Medical Journal, Professor Susan Bewley, consultant obstetrician at King's College, London, agreed. She writes that she found the NHS leaflets "exaggerated benefits and did not spell out the risks", adding: "The oft-repeated statement that '1,400 lives a year are saved' has not been subjected to proper scrutiny. Even cancer charities use lower estimates."

She wrote to Sir Mike: "I am not convinced that you have challenged your experts competently and mercilessly, rather than hidden behind them. Thus I support the calls for an independent review of the evidence - a review that will not be kicked into the long grass, whose findings will be widely and properly disseminated, and that will adjust screening policy appropriately and will lead to proper pursuit of the research implications."

In a letter of response, also published in the journal, Sir Mike revealed the initiative which he instigated "some weeks ago".

Sir Mike said that "screening programmes should be based on the best available evidence". Based on current advice, breast screening saves lives and the benefits considerably outweigh the harms. But he said he believes that the controversy should be resolved, so he launched the review. Once concluded, it will be presented to experts from both sides of the argument.

"I hope this reassures you that I take the current controversy very seriously," he wrote. "I will do my best to achieve consensus on the evidence, though I realise this may not ultimately be possible."

He added: "Should the independent review conclude that the balance of harms outweighs the benefits of breast screening, I will have no hesitation in referring the findings to the UK National Screening Committee and then ministers."

A Department of Health spokesman said: "Our advice has not changed - we urge all women to go for breast screening when invited. The best available evidence shows that screening saves lives by detecting cancers earlier than they would otherwise have been."