Junior doctors in England started their first ever all-out strike Tuesday in a bitter, deadlocked row with Prime Minister David Cameron's government over pay and conditions. The strike will have a major impact on the National Health Service (NHS), which employs more than 50,000 junior doctors — graduates with years of experience who have not yet completed their professional qualifications. While there have been several recent walk-outs, this one will affect hospital emergency care such as accident and emergency (A&E) and maternity units for the first time, although senior doctors and nurses will still be on duty. Nearly 13,000 operations and 113,000 appointments have been postponed around the period of the strike, which runs from 8:00 a.m. to 5:00 p.m. (0700 GMT to 1600 GMT) on Tuesday and Wednesday. "Anything unprecedented like this places a significant pressure on the NHS," Anne Rainsberry, national incident director for NHS England, told BBC radio. "The NHS has done everything it possibly can to mitigate that, but you can never say that it has mitigated it completely," she added. The British Medical Association (BMA), the doctors' trade union, has not ruled out a permanent strike or mass resignations as a way of trying to force the government's hand over the new staff contract on offer. A key sticking point has been on how much financial compensation junior doctors should get for working on Saturdays. "This is the saddest day of my professional life," said registrar Fiona Martin, 36, one of tens of protesters outside St Thomas' Hospital in central London, in the shadow of parliament. "I never thought as a doctor I would be forced to put down my stethoscope but we have been forced into it by a government that refuses to listen," she said. But Health Secretary Jeremy Hunt said the new contract was a "very fair deal" that rewarded junior doctors better than paramedics, police officers and fire officers for working unsociable weekend hours. "Given that, is it proportionate or appropriate to be withdrawing from patients who depend on them so much?" Hunt told BBC radio, accusing the BMA of "blackmailing" the government. "We have too many heartbreaking stories, parents who have lost children, people who have lost loved ones, because we are not delivering high-quality care at the weekend." The taxpayer-funded NHS, established in 1948, is one of Britain's most respected institutions, providing largely free medical care. While it has been protected from austerity cuts to public services under Cameron, experts warn it still faces increasing financial strain due to factors like rising treatment costs and an ageing population. Cameron's government argues that reforms to junior doctors' contracts are necessary to ensure that the quality of care for patients is as high at weekends as it is during the week. The prime minister has quoted research claiming mortality rates for patients admitted to hospital on a Sunday can be 16 percent higher than on a Wednesday, though doctors question this. An Ipsos Mori poll for BBC News found that 57 percent of the general public supported the doctors while a quarter opposed their actions. Hunt announced in February that he intended to impose the new contract on junior doctors after they rejected his "best and final offer." He launched a last-ditch appeal to them to stop the strike in the House of Commons on Monday, saying: "The impact of the next two days will be unprecedented." But there are signs the dispute is getting more entrenched. The health spokeswoman for the main opposition Labour party, Heidi Alexander, said there was "no trust left" between Hunt and junior doctors. She compared his handling of the strike to "pouring oil on a blazing fire." "Both sides seem to be digging in their heels," said Katherine Murphy, chief executive of the Patients Association. "They must now put aside their past stances and get together round the table to find a way forward in order to end the uncertainty that patients are facing."