A health think tank has warned that the government policy of not allowing patients to pay for drugs to top up their NHS care is "untenable".
Patients should be able to pay privately for drugs that have been rejected for use on the NHS due to high costs "in certain circumstances", the King's Fund said.
Under current policy, patients who wish to pay privately for drugs can be barred from the normal package of NHS care.
However, the King's Fund believes that if patients wish to pay for any treatment over and above what they would have normally received, it should not prevent them from accessing the rest of their treatment on the NHS.
The think tank's statement was released to coincide with a debate on the issue at its offices in central London which was attended by leading figures in health and social care, including Professor Sir Mike Richards, who is conducting a review of the issue for the government which will report in late October, and Andrew Dillon, chief executive of the National Institute for Health and Clinical Excellence.
The debate follows a High Court ruling this week that a cancer patient with just a couple of months to live should be given access to the life-prolonging drug Revlimid.