The walkout, which will take place from July 13 to 18, marks a dramatic escalation of the British Medical Association's dispute with the UK government over pay and staffing.
The announcement was made as a survey showed that junior doctors report being inundated with more opportunities to move abroad in the last four months than ever before.
Slightly more than half of about 2,000 junior doctors surveyed said they have received more job advertisements from recruiters for overseas roles since strikes were announced.
The government of South Australia even paid for trucks to be sent to junior doctor picket lines carrying job adverts offering improved pay if those doctors emigrated, it was revealed.
Co-chairs of the BMA junior doctors committee Dr Robert Laurenson and Dr Vivek Trivedi said that it was "shameful" that the government allowing the health service to "decline to point of collapse" with decades of real-terms pay cuts.
“With the 75th birthday of the NHS just days away, neglect of its workforce has left us with 7.4 million people on waiting lists for surgery and procedures, 8,500 unfilled doctors’ posts in hospitals, and doctors who can barely walk down the road without a foreign government tempting them to leave an NHS where they are paid £14 per hour for a country which will pay them properly.
“What better indication of how committed they are to ending this dispute could we have? As their refusal to even discuss pay restoration leads to continued disruption to the health service, more than four-fifths of junior doctors report finding their patients supportive – they understand the value of a fully staffed and resourced NHS," the doctors said.
“We are announcing the longest single walkout by doctors in the NHS’s history – but this is not a record that needs to go into the history books."
The government can avert the strike action by coming to the table with a credible offer on pay restoration, they said.
“Restoring pay can stem the flow of Australian job adverts in doctors’ social media feeds – and lead to a future 75 years of doctors being paid fairly, in a rebuilt workforce and NHS that this country can continue to be proud of.”
Downing Street said the planned strike action is concerning.
The Prime Minister’s official spokesman said: “It puts patient safety and our efforts to cut waiting lists at risk. It is obviously extremely disappointing.
“In the meeting the Government had with junior doctors, we made a fair and reasonable opening offer.
“We were discussing both pay and non-pay issues. But they chose to end the talks by announcing new strike dates.
“Obviously if they cancel the damaging and disruptive strikes and show willingness to move away from their starting positions and find a way forward, then we will be able to proceed with those discussions.”