Junior doctors in England are staging an all-out strike for a second day in a dispute with the government over a new contract, with more than 13,000 operations to be postponed.
The strike, from 8am to 5pm, was the fourth industrial action by doctors since the start of the year but the first to be extended to hospital emergency units.
21,600 junior doctors took part in the first day of the strike yesterday, 78% of the number who had been due to work.
British Prime Minister David Cameron condemned the strike called by the British Medical Association union as the "wrong thing to do", but public support remains strong.
A new YouGov poll for The Times found 52% percent of respondents blamed ministers for the dispute, compared with 9% who blamed the BMA.
A further 27% blamed both equally.
There are 53,000 junior doctors, graduates with years of experience but who have yet to complete their training, in England's National Health Service.
The taxpayer-funded NHS, which is administered differently in Wales, Scotland and Northern Ireland, was established in 1948 and is one of Britain's most respected institutions, providing largely free medical care.
While it has been shielded from austerity cuts to public services, experts warn it still faces increasing financial strain due to factors like rising treatment costs and an ageing population.
Mr 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.
Several thousand junior doctors took part in a demonstration yesterday outside Mr Cameron's Downing Street residence, where they were joined by Labour opposition leader Jeremy Corbyn.