Thousands of junior doctors have gone on strike across England as the dispute with the Government over pay deepens.
The 72-hour walkout by medics runs until 7am on Saturday and is expected to lead to thousands of NHS appointments and operations being cancelled.
They are demanding a 35% pay hike but the Government has offered just 5%.
It comes as NHS chiefs warned the number of people seeking emergency help will rise as the hot weather continues across the UK.
NHS leaders said urgent and emergency care will remain the priority.
NHS England medical director Professor Sir Stephen Powis warned: “We’re keeping emergency services as normal – maternity services, trauma – but of course there will be a lot of disruption to regular care.”
Around 50,000 appointments a day were disrupted during a four-day strike by junior doctors in April, with the latest industrial action set to have a similar impact.
Sir Stephen called on the Government to publish the long-promised NHS workforce plan.
“For us the long-term workforce plan, which we’ve been working on at the request of the Chancellor, is really important and we hope that the Government will be publishing that very soon,” he said.
“It takes a long time to train some staff, particularly doctors, so we need to plan well in advance.
“I’ve said previously that I want to see the number of medical school places expand.”
Shadow Health Secretary Wes Streeting said Rishi Sunak should have time to sit down with striking junior doctors if he has an hour “to sit with Boris Johnson negotiating gongs for cronies”.
Asked about the walkouts, Mr Streeting said: “I think the reason junior doctors are out on strike is because they don’t have someone to negotiate with.
“I think the question at this stage, having failed to get to a negotiated settlement, is where’s the Prime Minister?
“If he’s got an hour of his time to sit with Boris Johnson negotiating gongs for cronies and peerages in the House of Lords, he should have an hour at least to negotiate an end to these terrible strikes which are causing misery for the doctors involved and even more importantly misery for patients who are seeing their operations delayed and cancelled.”