Stephen Hawking, Robert Winston and a number of senior doctors are urging Theresa May to hold an inquiry into Jeremy Hunt’s claim that 11,000 patient deaths a year are caused by a lack of medics on duty in hospitals at weekends.

In a letter to the Guardian they claim the health secretary has caused a “devastating breakdown of trust between government and the medical profession” by misrepresenting the evidence on the “weekend effect”.

Hunt has come under fire since he began maintaining last year that “there are 11,000 excess deaths because we do not staff our hospitals properly at weekends”. Critics, including the British Medical Journal, have rejected his claim and accused him of highly selective use of complex evidence about the higher number of patients who die within 30 days of being admitted to hospital on a weekend.

The letter is a significant new challenge to Hunt’s integrity over the weekend effect and what lies behind it.

Its authors want the prime minister to order an independent inquiry into the process behind the definition and claims of a weekend effect. They say there is so much disagreement about the evidence underpinning the weekend effect claims that ministers should pause the new junior doctors’ contract and the push to create “a truly seven-day NHS”.

Physicist Stephen Hawking. Photograph: National Geographic Channels/Pau

Hunt’s assertion of a weekend effect due to understaffing is important politically because he has consistently used it to justify imposing the unpopular new contract on England’s 54,000 NHS junior doctors and the government’s push to make more NHS services in England available at weekends. The latter was a key Conservative pledge in last year’s general election campaign.

Other signatories to the letter include: Trish Greenhalgh, a professor at Oxford University specialising in evidence-based medicine; Prof Neena Modi, president of the Royal College of Paediatrics and Child Health; and Prof Alistair Hall, a cardiologist and epidemiologist at the Leeds teaching hospitals NHS trust.

They accuse Hunt of wasting NHS resources by forcing it to expand to a much fuller seven-day service on the basis of “bad evidence”, and of ignoring findings that challenge his thesis and misleading MPs and the general public.

“It is wrong to waste precious resources, or lives, because of bad evidence. Like NHS treatments, health policy should be evidence-based to demonstrate clinical and cost-effectiveness,” they write.

“Hunt has cherrypicked research, causing a devastating breakdown of trust between government and the medical profession. In making these claims without faithfully representing the evidence, he has obstructed fact and misled parliament and the public.”

Scientist Robert Winston. Photograph: Murdo Macleod/The Guardian

Other signatories include Dr Margaret McCartney, a prominent GP and an author, columnist and broadcaster on medical matters; Dr Phil Hammond, vice-president of the Patients Association; and several prominent junior doctors.

The doctors specifically dispute Hunt’s claim that eight research studies back up his concern that a lack of medics in hospitals at weekends is leading to large numbers of avoidable patient deaths.

The authors of the letter also want the prime minister to halt “any policies or contractual reform driven by this evidence until it can be examined objectively and with rigour”.

Prof Julian Bion, an expert in the weekend effect at Birmingham University, said a project he had been leading since 2014 was undertaking the sort of inquiry that the letter’s writers were seeking.

While not disputing the existence of a weekend effect, Bion said the causes of it were “multifactorial” and not simply due to too few doctors being on duty.

“There is evidence that patients admitted at weekends are sicker and the weekend effect may therefore have a ‘community dimension’,” he said. “The causes may include [the availability or not and quality of] community and social care as much as hospital care.”

Paul Aylin, another expert in weekend-related mortality and a professor at Imperial College London, said there were many “studies out there of varying quality, and people therefore have plenty to pick from to support their side of the argument”. But international evidence showed a weekend effect in patients who had a gastrointestinal haemorrhage, stroke, heart attack, arrhythmia or cardiac arrest, but not in neonatal deaths, he said.

A Department of Health spokesman rejected the authors’ concerns. “Over the past six years we have been presented with clear independent evidence of variation in care across the weekend. This government makes no apology for tackling the issue, to build a safer seven-day NHS for patients,” he said.

“Further peer-reviewed evidence is emerging all the time, including the authoritative 2015 Freemantle report, which confirmed previous evidence of a weekend effect.”