Drugs costing just eight pence a day could be denied to NHS patients under “devastating” new rationing plans, charities have warned.

Under the plans, health officials will be able to delay introducing life-extending treatments for up to three years, after they have been found to be effective.

The cap is likely to affect one in five new treatments, with cheap drugs which could help large numbers of patients affected, as well as high cost drugs.

Under the new rules, any medications likely to cost the health service more than £20m a year will be subject to a new tier of bureaucracy.

At present, the NHS has 90 days to make drugs available to patients, once they have been given the green light by the National Institute of Health and Care Excellence (Nice).

The new system will allow health officials an extra three years to introduce drugs, during which time they will try to negotiate cost reductions.

Last night charities accusing the Government of abandoning a manifesto pledge to speed up access to drugs, which could leave patients to die while vital treatment was kept out of reach.

Seven treatments authorised in the last two years for more than 250,000 patients would have been hit by the cap, analysis shows.