Nick Clegg, the Liberal Democrat leader, will set out today why he believes patients should be allowed to pay privately for drugs to “top up” NHS care.

The Liberal Democrats will seek to outflank both Labour and the Tories after patients who bought life-extending cancer drugs privately were refused further treatment by the NHS.

Under current guidelines, patients risk forfeiting their right to NHS care, such as nursing or chemotherapy, if they pay privately for treatment rejected or not yet approved by the National Institute for Health and Clinical Excellence (NICE).

The Government is expected to publish a much-anticipated review of its policy on so-called co-payments next month. But the Liberal Democrats are the first political party to say that they would give patients the option to pay for drugs without jeopardising the rest of their care. The Conservatives have adopted a markedly more cautious approach to the issue.

At their conference next week the Liberal Democrats will seek to emphasise their progressive credentials and willingness to look at more market-based solutions to problems.

Mr Clegg will say today that new Labour is “dead in the water”. The party claims that voting Liberal Democrat in certain parts of the country is the only way to oust Labour.

He justifies his belief that patients should be allowed to “pay the difference” as part of a wider liberal philosophy. He will say: “We cannot continue to deny people the right to top up their care, particularly where they are following their clinician’s advice. An extra week of life may not count for much on a bureaucrat’s chart. But if you’re saying goodbye for ever to your children, it couldn’t matter more.”

Mr Clegg will be speaking at the market-orientated think-tank Reform, which is launching a pamphlet exploring insurance-based funding of the health service. It proposes a new national health protection system, where individuals would be able to invest up to £2,000 a year to guarantee their healthcare.

Many Labour MPs and unions oppose co-payments, saying that they would lead to a two-tier NHS where only richer patients could afford effective but high-cost treatments.

At present, some hospitals allow patients to top up their care while others do not.

After mounting criticism over the variations, Alan Johnson, the Health Secretary, asked Mike Richards, the national cancer director, to review co-payments.

Professor Karol Sikora, of Cancer Partners UK, estimates that the rising bill for cancer drugs could cost the NHS £50 billion, half the current budget for the entire health service, within four years. “£50 billion is the equivalent to raising tax by 15p for everybody. That’s the bottom line,” he has told Sky News.

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