The Government has not ruled out imposing a new contract on junior doctors if their dispute over new terms and conditions cannot be resolved in talks, Prime Minister David Cameron has said.
Mr Cameron said that giving up the option of imposing a contract would effectively hand a "veto" to the British Medical Association over the future development of the NHS.
Following a 24-hour walkout leading to the cancellation of around 4,000 operations last week, junior doctors are threatening two further strikes in their row over Government plans for more seven-day working.
Talks are under way to try to avert a 48-hour stoppage with the provision of emergency care only due to start on January 26, as well as a full withdrawal of labour, including emergency services, from 8am to 5pm on February 10.
Mr Cameron told BBC Radio 4's Today programme that further strikes are "unnecessary and damaging", and his administration is "still happy to negotiate and talk".
Asked if he would impose new conditions on junior doctors if it proved impossible to reach agreement, the PM said: "We can't rule that out because we can't simply go into a situation where the junior doctors have a complete veto and block over progress in our NHS.
"But we are talking to them in very good faith. I think we've settled 15 of the 16 issues that they raised. There's an 11% basic pay rise on the table.
"So I would urge them to get round that table and have that final negotiation... I don't want this strike situation to continue, what I want is what I put in our manifesto, which is a more seven-day NHS, for which we do need some contract changes."
He added: "This is all a matter for discussion between the doctors and the health service managers and let's hope it doesn't come to that. But if you rule out ever imposing a contract, you are basically giving a veto to the BMA over what the situation will be in future, and we can't do that. We have a manifesto commitment to a seven-day NHS."
Under the new contract, "75% would get a pay rise, no-one working legal hours would get their pay cut, we are not reducing the overall junior doctors' pay bill overall," said Mr Cameron.
"We are still happy to negotiate and talk and we think these strikes are unnecessary and damaging."
The PM told Today: "If you have a stroke at the weekend, you are 20% more likely to die, so it is important to have a more seven-day NHS and this junior doctors' contract helps with that."
Ministers' use of the 20% figure has been challenged by the BMA and 2,000 doctors have written to the Government to complain about suggestions that there is a clear link between junior doctor staffing levels and "excess deaths" at the weekend.
NHS medical director Sir Bruce Keogh has said it is not possible to say how many of the deaths may have been preventable.
But Mr Cameron insisted: "Every single doctors' organisation, including the BMA, has said that there is a problem with the NHS at the weekend. The doctors know it, the patients' organisations know it, the health service managers know it.
"That's what this is all about - trying to overcome that problem, because there are issues with people having less good outcomes if they present themselves at a hospital at the weekend.
"That's not to blame junior doctors. It's often because there isn't the right balance between consultants and junior doctors, or we are not using all the equipment in the NHS properly at the weekend."