Excessive death rates at 25 hospital trusts should be probed by the government, one of Britain’s leading experts on the subject has said.

The Department for Health insisted it is already taking “tough” action against underperforming hospitals after Professor Sir Brian Jarman said thousands more patients had died between 2007 and 2008 than would normally be expected.

My main concern is that the government only focuses on self-inspection rather than launching wider inquiries

Sir Brian, a former member of an inquiry into the deaths of heart patients at Bristol Royal Infirmary who is now an emeritus professor at London’s Imperial College School of Medicine, said that after 10 years of “no action, I needed to say something”.

He warned current regulation is “fundamentally flawed” but added that high death rates do not necessarily prove hospitals are doing anything wrong.

He said: “My main concern is that the government only focuses on self-inspection rather than launching wider inquiries. That is why I have decided to take action.

“An investigation may not prove anything is being done wrong but it could still boost our ability to reduce death rates.”

Sir Brian said each of the trusts he highlighted had at least 150 more deaths than expected in the year 2007-08. Across the 25 trusts, there were 4,600 unexpected deaths in total.

The government defended its record on hospital regulation.

A Department of Health spokesman said: “We are confident that any concerns about underperforming hospitals will be thoroughly investigated by the regulator, the Care Quality Commission. We have armed them with powers to take tough enforcement action to make sure all hospitals give patients high quality care.