Concerns have been raised over the privacy of patients' medical records, which are to be stored on a new NHS computer database.
A patient's records could be accessed, wherever they are, under the system
Q: What is happening?
The database, which is being installed as part of the NHS's IT upgrade, is designed to allow doctors and nurses to access a patient's records wherever they are.
It hopes to connect every family doctor and hospital in England, and provide online records for 50m patients by 2010.
Patients should also be able to book appointments and operations over an electronic booking system.
The government is also aiming to set up a system for the electronic transfer of prescriptions, and look at ways of storing and distributing digital images, such as X-rays, to help diagnosis and treatment.
The total cost of modernising the NHS computer system could be between £18.6bn and £31bn.
Q: What are the concerns over privacy?
In January ministers said patients would be able to opt out of the new system completely, or restrict access to their records, to protect their privacy.
However, in an email to a Warwickshire GP, Phil Walker, the Department of Health's head of digital information policy, said patients would not have the right to veto what was recorded about them, or in what format the information was kept
Q: So what is happening?
'Patients' Tsar' Harry Cayton said patients cannot determine what is recorded, but they can say how they want that data stored and who they want to have access to it.
Doctors have to record consultations with patients, under General Medical Council guidelines, Mr Cayton said.
But he told the BBC's Today programme: "How that is stored, and who it is shared with, is a matter between you and your doctor."
The Department of Health said patients will have the right to "seal" away parts of their records, so no other medical staff can see them without their permission.
However, this could be over-ridden in an emergency.
The patient could also ask for certain information not to be recorded at all.
But again, the doctor could over-ride this, as GPs are obliged to keep adequate and accurate records about patients' health and treatment.
Q: But can patients still opt out of the database?
Harry Cayton says they can. He chairs a board which is advising the government on how the computerised records system should be introduced, and how patients' rights can be protected.
He said: "You will be able to opt out of the new system entirely, if you wish.
"But of course, there will be consequences which you will need to understand and to discuss with your GP."
He said he had recommended to ministers that patients be given a Care Record Guarantee which would set out how their data would be collected, stored, shared and how consent might be given or refused.
Q: Have these reassurances been seen as satisfactory?
The British Medical Association has said it wants the situation to be clarified in the wake of the email from Phil Walker.
It said it wanted to be reassured that, as the government had stated previously, patient confidentiality would be respected, and that no information would be revealed after a consultation without the patient's permission.