Junior doctors are to stage five days of strikes with "full withdrawal of labour" over the controversial new contract for training medics, doctors' leaders have announced.
The strikes will take place between the hours of 8am and 5pm for five days between Monday September 12 and Friday September 16, the British Medical Association (BMA) said.
This action will be followed by "further dates" which are yet to be confirmed, a BMA spokeswoman said.
The Department of Health accused the BMA of "playing politics in a way that will be immensely damaging for vulnerable patients".
However, the BMA said junior doctors had been left with "no choice" but to start fresh strike action after failed attempts to resolve the remaining issues with the contract.
Six strikes have already taken place across England during the dispute, causing disruption to hundreds of thousands of patients who have had appointments and operations cancelled.
In May, it looked as though a breakthrough had been reached in the dispute after both sides agreed to a new deal.
Then in July, the Government announced it would impose a new contract after junior doctors and medical students voted to reject the contract brokered between health leaders and the BMA.
The BMA said it will call off the strikes if the Government agrees to stop the imposition.
Dr Ellen McCourt, who chairs the BMA junior doctors' committee, said: "Junior doctors still have serious concerns with the contract, particularly that it will fuel the current workforce crisis, and that it fails to treat all doctors fairly.
"Since July, the BMA has made repeated attempts to work with the Government to address the concerns that junior doctors have raised about the contract. Genuine efforts to resolve the dispute through talks have been met with an unwillingness to engage and, at times, deafening silence from the Secretary of State, leaving junior doctors with no choice but to take further action. This is despite a pledge from Jeremy Hunt that his door is always open.
"The Government has consistently said this is about creating a seven-day NHS, when junior doctors already work weekends and it's been shown that the Government has no answer to how it will staff and fund extra weekend care.
"With just weeks before the first group of doctors is moved onto the imposed contract, time is running out. This contract will be in place for many years, it will have a direct impact on patient care and whether we can attract and keep enough doctors in the NHS. It is too important to be rushed to meet a political deadline.
"We have a simple ask of the Government: stop the imposition. If it agrees to do this, junior doctors will call off industrial action.
"This is not a situation junior doctors wanted to find themselves in. We want to resolve this dispute through talks, but in forcing through a contract that junior doctors have rejected and which they don't believe is good for their patients or themselves, the Government has left them with no other choice."
A Department of Health spokeswoman said: "As doctors' representatives, the BMA should be putting patients first not playing politics in a way that will be immensely damaging for vulnerable patients. What's more, the BMA must be the first union in history to call for strike action against a deal they themselves negotiated and said was a good one.
"Whilst there are many pressures on the frontline, funding is at record levels, with the highest number of doctors employed in the history of the NHS. Co-operation not confrontation is the way forward to make sure patients get the best treatment and the NHS is there for people whenever they need it."
Shadow health secretary Diane Abbott said Jeremy Hunt should "scrap" the contract and re-enter talks with junior doctors.
"Given the intransigence of the Government, this decision was always likely," she said.
"The crisis in the NHS is deepening, with closures of hospitals and key departments across the country while nearly all waiting times are rising.
"The Government is not properly funding even a five-day NHS. A seven-day NHS is simply impossible without more resources.
"It is not too late to change course. Jeremy Hunt should stop posturing about imposing a junior doctors' contract, scrap it, and re-enter talks."
Mr Hunt told BBC News: "This is devastating news for patients.
"Perhaps 100,000 operations will now have to be cancelled.
"Around a million hospital appointments will have to be postponed causing worry, distress and anxiety for families up and down the country."