The Tories have been challenged over their promise to fund new cancer drugs.

The party has vowed to give patients access to treatments that are licensed and widely available in Europe but have not been approved by the National Institute for Health and Clinical Evidence.

As this increase has not yet been implemented and given other pressures on the NHS budget, the £200m funding would need to be generated by planned cash-releasing efficiency savings

The Tories said the estimated £200m a year cost would be met by savings the NHS will make as an employer under the party’s plans to scrap next year’s National Insurance increase.

But the King’s Fund think tank claimed the money would have to come from cuts elsewhere in the NHS budget.

A spokesman said: “The Conservative Party have made clear in their proposals that the funding that would otherwise go to pay for increased National Insurance contributions from April 2011 would be used to create a cancer fund.

“As this increase has not yet been implemented and given other pressures on the NHS budget, the £200m funding would need to be generated by planned cash-releasing efficiency savings.”

King’s Fund chief economist Professor John Appleby added that oncologists were divided over whether there should be wider access to certain cancer drugs, as the NHS had to make the best use of limited financial resources.

But shadow health secretary Andrew Lansley said: “We have been very clear we are going to protect the NHS budget, we are going to increase the budget each year in real terms, so within that budget from next year onwards the employers in the NHS don’t have to spend £200m plus on an increase in National Insurance, they will have that money available to meet other needs.”