British patients should adopt more "pushy" American attitudes with their doctors to get drugs they are entitled to, the head of the NHS rationing body has said.

Prof David Haslam, chairman of the National Institute of Health and Care Excellence (Nice), said that patients need to see themselves as "equal partners" with doctors to get the treatment they need.

And he explained that after working as a doctor near an US air force base in Cambridgeshire, he noticed that American patients had a less deferential approach than local residents.

"Americans tended to want to know more about their treatment than the British who tend to be much more 'thank you doctor, I will take that'," he told the Daily Telegraph.

Earlier this week a government report found that a third of patients with kidney cancer and one in three motor neurone disease sufferers are not receiving the drugs they need.

Health experts warned that the research by the Health and Social Care Information Centre had exposed an "endemic and disastrous postcode lottery" of care within the health service.

Prof Haslam said an investigation was under way to uncover why so many patients are not being prescribed medications .

But he explained that patients should demand the drugs they need and only be refused Nice-approved drugs if they are unsuitable

He said that, although he was not suggesting that patients should be confrontational, he wanted them to tell doctors if they think they are missing out on treatments which could help them.

He said: "When products have been approved for use by the NHS by Nice, patients have a legal right to those drugs – as long as they are clinically appropriate. The take-up should be much higher than it currently is."

The former GP also urged people to have a better understanding of the drugs they are taking or might be able to take, allowing them to work better with their doctor.

He added that it was "essential for the future of the health service and the future health of the nation" for patients to understand their conditions and treatments.