Strikes by junior doctors are “very disappointing”, the Prime Minister said as he asked why doctors in training are “refusing to accept something that everyone else is now accepting”.

Rishi Sunak said junior doctors in England are the “only remaining people” yet to settle their pay dispute.

Junior doctors from the British Medical Association (BMA) will take to picket lines from 7am on December 20 to 7am on December 23 in a major escalation of the dispute over pay.

Doctors in training are also planning to stage the longest strike in NHS history in January – for six whole days starting on January 3.

Mr Sunak told the Commons Liaison Committee the walk outs are “very disappointing”.

“We have now reached a resolution with every other part of the public sector and every other part of the NHS, so over a million workers through the Agenda for Change deal that we did several months ago, including all our nurses, and then most recently with consultants and the other doctor grades,” he said.

“So the only remaining people who have not settled are the junior doctors.”

Mr Sunak said the Government has “demonstrated its considerable reasonableness” in reaching resolutions with other public sector workers.

“The question more is for the junior doctors, as to why they are refusing to accept something that everyone else is now accepting, on top of having a pay increase which is more generous than anyone else’s set by the independent body going into this.”

The NHS said that in the coming three weeks only two weekdays in the NHS are unaffected by holidays or industrial action.

It comes at one of the busiest times of the year for the NHS as it grapples with increased pressure from winter viruses including flu, Covid-19 and norovirus.

The NHS has said emergency and urgent care will be prioritised during the strikes and “almost all” routine care will be affected.

But one A&E will temporarily shut because of strikes.

Gloucestershire Hospitals NHS Foundation Trust said Cheltenham A&E will temporarily shut at various points in the coming weeks because of the strikes.

It said in a statement that emergency care services (A&E) will be “centralised” at Gloucestershire Royal Hospital because of the “substantial challenges” posed by the industrial action.

“The local NHS has today warned that the latest round of strikes scheduled for December (three days) and early January (six days) will pose substantial challenges to hospital services at the busiest time of the year and the impact will be felt well into the New Year,” the trust said.

“After careful consideration, health leaders have set out the temporary service arrangements that will be put in place for the coming weeks.”

Professor Sir Stephen Powis, national medical director for the NHS in England, said earlier on Tuesday: “These strikes come at a time that will cause huge disruption to the NHS, with services already feeling the strain of winter pressure.

“When you factor in the Christmas and New Year break, these strikes will prolong that period of reduced activity and it also puts the health service on the back foot into the new year, which is a time where we see demand start to rise significantly.

“Over the holiday period, I would encourage anyone who needs medical help to continue to come forward – in a life-threatening emergency call 999 and use A&E in the usual way. For everything else, use 111 online.”

Mr Sunak’s official spokesman said: “We would encourage junior doctors to consider carefully the extremely significant impact striking at such a challenging time will have, both on the NHS and for individual patients, and to return to talks.

“I know the Health and Care Secretary is very open to continuing discussion.”

BMA junior doctors committee co-chairmen Dr Rob Laurenson and Dr Vivek Trivedi said in a statement on Tuesday: “The Government can still avoid the need for these strikes: we will be ready and willing any time they want to talk. If a credible offer can be presented the day before, or even during any action, these strikes can be cancelled.

“Every winter we raise the alarm about the NHS and every winter the Government fails to put the necessary investment into staff to prevent the crisis – now is the time to break the trend.”

Consultants in England are voting on a deal struck between the BMA and the government, but in case the deal falls through, they have renewed their industrial action mandate.

On Monday, the BMA said it has also come to a deal with the Government on pay for specialist, associate specialist and speciality (SAS) doctors, but it also announced that SAS have voted to take industrial action if the offer is rejected.