The government has bowed to privacy concerns about a new NHS computer system and conceded that patients should be allowed a veto on information about their medical history being passed from their GP to a national database.

Following a Guardian campaign against the compulsory uploading of personal details to the system known as The Spine, Lord Warner, the health minister, will announce a plan that would allow individuals to review and correct their records and withhold them from the database.

Critics fear that details about mental illness, abortions, pregnancy, HIV status, drug-taking or alcoholism could become vulnerable to prying by the police, insurance companies and hackers working for the press. This month the Department of Health sent more than 1,300 curt letters rejecting requests from patients for their medical details to be kept off the national database. But ministers have changed their minds after advice from a taskforce on patient records headed by Harry Cayton, the department's "patient tsar".

Under his scheme, GPs would ask every patient to give their explicit consent for a summary of their record to be put on the national database. They would be given a few weeks to review the summary and call for corrections or amendments to be made before they consented to the upload.

In a key departure from the previous position, the taskforce said: "Some patients may ask for their summary care record not to be shared or uploaded at all."

Lord Warner said it was not yet possible to guarantee a right of veto. Some doctors were concerned that patients might be putting themselves at risk by refusing access to records that could save their lives in an emergency.

Others feared that the system could throw up unreliable statistics about the efficacy of medicines and treatments if too many patients opted out.

But he conceded it was technically possible for patients to refuse to let their data be uploaded and the government was considering how to make this happen.

Mr Cayton has allayed the concerns of the British Medical Association about patients who do not respond to a request from the GP asking if they consent to their medical summary becoming available on the database for use throughout the NHS.

The taskforce report says: "After a realistic period, it would be assumed that those patients who have chosen not to view their record are giving implied consent for it to be shared."

Under the government's original proposals, patients would have been given the right to put some or all of their medical details in a "sealed envelope" on the database, denying access to doctors, nurses and paramedics, or limiting the circumstances in which they could access it.

Civil rights campaigners feared that the security of the electronic seal was suspect, making the information vulnerable to hackers or unauthorised use by government agencies.

The government was proposing to start uploading patients' records before the technology for sealing the information was proved. A Medix opinion poll of GPs, commissioned by the Guardian, found that 60% thought the confidentiality of the records was at risk and 50% threatened to defy government instructions to upload the data.

Lord Warner said the government remains firmly committed to the creation of a national database and hopes to persuade the vast majority of patients to consent to their records going on it.

A public information campaign will be launched shortly, claiming that lives could be saved in emergencies with instant access to information about patients' allergies, medications and previous treatments.

The new proposals will not change the government's plan to upload patients' names, addresses and dates of birth to the national database. Ministers say the NHS needs a list of who is entitled to free treatment and has legal authority to make this information accessible to authorised medical staff throughout England.

Lord Warner said 1,351 people wrote to Patricia Hewitt, the health secretary, demanding that their medical records should not be uploaded, using a form of words devised by Ross Anderson, professor of security engineering at Cambridge university, a leading critic of the scheme.

The government wants the first patient records to be uploaded in the spring, starting in two trial areas to be selected from 50 primary care trusts.