The Government has been accused of lying over NHS pay as hundreds of thousands of health workers including midwives, nurses, radiographers, cleaners and psychiatric staff stage their second strike in a month.
Members of 11 unions walked out for four hours from 7am in England and 8am in Northern Ireland in protest at the Coalition's controversial decision not to accept a recommended 1% wage rise for all NHS employees.
Picket lines were mounted outside hospitals and ambulance centres, and the stoppage will be followed by a work to rule for the rest of the week.
A new row flared after the Government said it had put forward proposals to guarantee all staff would get at least 1% this year and next, but it had been rejected.
Unions said that "simply wasn't true", pointing out it was the Coalition's decision not to accept a recommendation from the Pay Review Body (PRB) which sparked the dispute earlier this year.
Unison leader Dave Prentis, who joined a picket line outside the London Ambulance Service HQ, said: "It's ludicrous that the Government is keeping up the pretence that all staff are getting a 1% pay rise, and it doesn't matter how often they say it; it's simply not true.
"The fact is the independent NHS Pay Review Body recommended a 1% pay rise for all but this was rejected by the Government and now 60% won't even be getting a 1% pay rise.
"The PRB have kept the industrial peace for the past 25 years. The Government should pay up and stop playing games."
Rehana Azam, national officer of the GMB union, said: "Why does the Government continue to lie to health workers? If they want to pay 1% to all workers they would adopt the agreement by the Welsh Government to pay what the Pay Review Body said that they should."
A deal has been struck in Wales, following an earlier agreement in Scotland, leaving the dispute only affecting England and Northern Ireland.
Pictures from last month's strike
A Department of Health spokesman said: "NHS staff are our greatest asset and we want to make the current pay system fairer - which is why we have put forward proposals that would guarantee all staff would get at least a 1% pay rise this year and next, but these have been rejected by the unions.
"We have taken tough decisions to increase the NHS budget, but we can't afford a consolidated pay rise in addition to increments without risking 10,000 frontline jobs."
Mr Prentis said: "The fact almost all health unions are taking part in the industrial action should ring alarm bells in Whitehall.
"The anger is spreading and so is the public support for health workers' cause. The strength of feeling is far from fading and the dispute far from going away.
"All the Government has done so far is threaten workers with job cuts.
"If the Secretary of State seriously thinks staff are the NHS's best asset then he needs to treat them fairly. We are only asking for decent pay for the hard-working people the Government say they care so much about.
"There will be plenty of opportunities for Jeremy Hunt to go in trusts around the country to meet with staff who will be working to rule, taking away the goodwill the NHS relies on so much.
"NHS workers in Scotland and Wales will all be getting a 1% pay rise and the Living Wage. So why is the Secretary of State so determined to penalise workers in England?
"The Government and NHS Employers need to engage in meaningful talks about how to resolve this dispute. We are prepared to keep up the pressure through the winter and up until the general election."
By the end of the next financial year, health workers will have had their pay capped for six years, said the TUC.
General secretary Frances O'Grady, who joined Mr Prentis on the picket line, said: "Health workers care passionately about their patients and the quality of service they provide, and so are always reluctant to take action.
"But the Government's refusal to accept the recommendations of NHS independent pay review body - even though it only called for an affordable, below-inflation pay rise - leaves health workers feeling that they have no other option.
"It's not too late for the Government to change course and award health workers the pay rise the public knows they deserve."
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