Hospitals are cancelling tens of thousands of appointments and operations after resident doctors voted overwhelmingly to reject a last-ditch government offer to avoid this week’s strike.

The health secretary, Wes Streeting, and the British Medical Association (BMA) are being urged to agree to see if an independent mediator can break the deadlock in the almost three-year-old pay and jobs dispute in England.

NHS bosses are anxious about how hospital services will cope with what will be the 14th stoppage resident – formerly junior – doctors have staged since March 2023 when it is already struggling to cope with a fast-growing “flu-nami”. They have had to reschedule an estimated 38,500 outpatient appointments and treatments, including surgery, chemotherapy and radiotherapy for cancer.

They also fear that consultant (senior) doctors will be too busy covering the work of their more junior colleagues during the strike to help hospitals undertake their traditional pre-Christmas clearout of patients who are well enough to leave, so they can give their beds to others who need to be admitted during the cold snap that usually causes problems during the festive season.

The Patients Association called for third-party arbitration after resident doctors voted 83% to 17% against a deal the BMA called “too little, too late”. They had voted in a survey of opinion about an offer that, if accepted, would have led to the doctors union calling off their five-day walkout, which will now start as planned at 7am on Wednesday.

Arbitration could break the “endless cycle of disruption, cancellations and anxiety” that has existed since the dispute began in March 2023, the association’s chief executive Rachel Power said.

“It’s clear the current approach isn’t working. Independent mediation is the only credible path to a lasting solution that protects patients,” she said after the rejection.

“Both the BMA and the government must now commit to independent arbitration immediately. This must happen now. This cycle must end.”

A senior NHS official admitted that hospitals may be harder hit than during previous walkouts and unable to provide the 95% of planned, non-urgent care they did the last time.

Senior doctors will be stationed at the entrance to A&Es to encourage less seriously unwell patients to seek help elsewhere, such as with a GP, pharmacy or urgent treatment centre.

The doctors’ rejection triggered a new round of verbal hostilities. Streeting decried resident medics for taking part in “self-indulgent, irresponsible and dangerous” industrial action. Their pursuit of a 26% pay rise, having already seen their salaries increase by 28.9% since 2022, was “a fantasy demand”.

His offer would have doubled the number of training places early careers doctors can apply for from 2,000 to 4,000, but did not include a further pay rise for 2025/26, which he has ruled out.

In a direct appeal to resident doctors, Streeting asked them to work normally this week, despite the union’s stance. “Abandoning your patients in their hour of greatest need does against everything a career in medicine is meant to be about.”

Keir Starmer said he was “very gutted” by the BMA’s “irresponsible” decision to press ahead with the walkout.

But the BMA hit back. In a comment piece for the Guardian the head of the BMA resident doctors committee chair decried “government spin” about the offer, said it would not result in the NHS having any more doctors and accused Streeting of using “disrespectful language” about them.

Dr Jack Fletcher said the government’s offer, made last Wednesday, involved simply “repurposing” existing “locally employed doctors” and amounted to “just shuffling the deck chairs on a sinking ship”.

The 4,000 places will do too little to end an NHS-wide “training bottleneck” of unemployed doctors that results from up to 40,000 of them competing with each other for only about 10,000 places to train in their chosen specialist area of medical practice, such as psychiatry, A&E or surgery.

The lack of training places is the result of “political choices” not to fund or staff the NHS properly, Fletcher added. In addition, the government’s pay offer to resident doctors for 2026/27 – a 2.5% uplift in their salaries, despite inflation being closer to 4% – represented a “real-terms pay cut”, he added.

Meanwhile, hospital bosses warned that the strike would harm patients and put them at risk, and urged the BMA to reconsider. “Despite NHS leaders working increasingly hard to prepare for these strikes, we are concerned if resident doctors walk out during a record flu surge it could put patient safety at risk,” said Rory Deighton, the NHS Confederation’s acute and community director.

“We would urge the BMA to recognise these strikes are disproportionate given the generous pay rises resident doctors have already had, call them off and moderate their demands so a solution to this long-running dispute can be found.”

Its timing makes this week’s stoppage difficult for the NHS. It is already facing its toughest winter in years as a wave of flu has left 2,660 people seriously ill in hospital – the most ever for the time of year – amid a warning from the NHS England chief executive, Sir Jim Mackey, that that could soon hit 8,000.

“We expect the operational impacts of this round of industrial action to be more severe due to the combination of winter pressures and proximity to Christmas,” NHS England’s national director for emergency planning, Mike Prentice, said in detailed guidance issued to the service on Monday on how to handle the strike.