The Government yesterday moved to reassure the public about the security of a new national patient information database as it was claimed an estimated 200,000 people are set to opt out of the system.

An IT programme to introduce the mass database has the "highest standards of security", a spokeswoman insisted.

She said said more than half a million people had been contacted so far in Bolton, Bury, Birmingham, Dorset and Bradford primary care trusts which are piloting the scheme to ask them if they want their medical records to be excluded.

Only 3,425, or less than one per cent had requested that their details should not be uploaded onto the database, she said.

She added the scheme would be evaluated before it is extended and all patients would be asked for permission to upload basic data from their GP records, such as current medication, allergies, and long term conditions.

They would be given options, she said, including refusing permission altogether or specifying that their records could only be accessed with their explicit permission.

She said: "We are confident that the IT systems have the highest standards of security control."

Her remarks come after a campaign group the Big Opt Out said it estimated 200,000 people have requested or downloaded documents allowing them to demand that their medical details are excluded from the database.

The news of requests comes after scandals over data security including the revelation in November that computer discs holding personal information on 25 million people and 7.2 million families had gone missing. Patient information has also been lost by nine NHS trusts, it has been revealed since then, as well as the details of three million learner drivers by a DVLA contractor.

Helen Wilkinson, of the Big Opt Out campaign, said she was concerned that patients were still largely unaware of their right to demand their details are excluded from the "spine" or national database of information.