Strikes by junior doctors in England will have a “significant impact” on patient care, Downing Street has said.

No 10 said the walkout comes at a “challenging time” for the health service as it urged junior doctors to return to talks.

The Prime Minister’s official spokesman said that Health Secretary Victoria Atkins was “very open to continuing discussion”.

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

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

And 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 Prime Minister’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.”

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

Professor Sir Stephen Powis, national medical director for the NHS in England, said: “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.”

BMA junior doctors committee co-chairs Dr Rob Laurenson and Dr Vivek Trivedi said in a statement: “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.”