Officials are to trawl the medical records of staff at the Dounreay nuclear site as the government inquiry into the removal of organs and tissue from dead workers in the atomic industry is expanded.

Last week, a row broke out when it was claimed 65 people, most of whom worked at Sellafield in Cumbria, had organs and tissue removed for analysis but without the knowledge or consent of their families.

Yesterday, Alistair Darling, the Trade and Industry Secretary, told MPs industry chiefs believed similar medical work was carried out at the nuclear site in Harwell near Oxford and "possibly at other sites", potentially involving non-nuclear workers.

A spokesman for the UK Atomic Energy Authority (UKAEA) told The Herald that it had "no information" to date to say that such work took place at Dounreay in Caithness but revealed it had set up a special team of workers to go through records from several sites, including the Scottish one, going as far back as the 1960s. "We will be looking for information from any of the sites," said the spokesman.

He added that all relevant details would be passed on to Michael Redfern, the QC who is leading the government inquiry.

As well as the UKAEA, which oversees five sites including Sellafield, Harwell and Dounreay, the Atomic Weapons Establishment (AWE) in Berkshire, which maintains the warheads of Britain's nuclear deterrent, is also checking its records.

In his statement, Mr Darling said: "The UKAEA tell me that they believe such work was carried out at Harwell at least until the early 1980s and possibly at other UKAEA sites, potentially involving work related to individuals who had not been employed at nuclear sites. The AWE believes that there could have been additional testing on their employees."

The Secretary of State set out the terms of reference for the inquiry, which will look into the circumstances in which organs and tissue were removed from 65 workers between 1961 and 1992.

He said the aim was to find out in particular who requested the testing and whether or not families gave their consent.

Mr Darling said the inquiry would also establish whether the families or surviving relatives were informed of the results of the testing as well as who authorised the analysis.

Charles Hendry for the Conservatives said expansion of the inquiry to look at other nuclear sites was "very disturbing". He noted: "It is now clear the removal of tissue samples was on a much larger scale than was first thought. Our sympathies are with the families involved at Harwell. Serious questions will need to be answered as to whether tissue samples were taken without proper consent or authorisation and why families were not informed."

Paul Noon of Prospect, the union which represents 12,000 scientists, engineers, technicians and managers in the nuclear industry, added: "Nuclear workers and their families at Harwell and other nuclear sites will be concerned at the news that the removal of organs and tissue was more widespread than originally revealed. We will be pressing for Michael Redfern to move with all possible speed to complete the inquiry."

In a statement, the UKAEA said it had told the DTI of its initial findings but was now "undertaking a more detailed search and review" and that it would look to complete this "as sensitively and speedily as possible".