Unions claimed "tremendous support" from health workers for a fresh strike over pay as a new row flared with the Government, worsening an already bitter dispute.
The coalition was accused of "lying" as hundreds of thousands of health workers including midwives, nurses, radiographers, cleaners and psychiatric staff, walked out in England and Northern Ireland for the second time in a month.
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 1% 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."
The Department for Health took issue with the unions' claims, insisting it was untrue to say 60% of NHS staff will not receive a 1% increase.
The 55% of NHS staff not receiving a 1% increase will get an incremental increase averaging 3% and rising to 6% for the highest, while the remaining 45% of staff will get a 1% increase this year and a 2% increase next year, according to the department.
The department has said unions are defending a pay system that "unfairly" rewards the highest paid, under which a senior manager can expect an increment of 6.8% in one year, jumping from £61,779 to £65,922, compared to a healthcare assistant who will receive an average of 2.5% each year, moving from £14,294 to £14,653 in one year.
Members of 11 unions walked out for four hours, with picket lines mounted outside hospitals and ambulance centres, while the stoppage will be followed by a work to rule for the rest of the week.
A deal has been struck in Wales, following an earlier agreement in Scotland, leaving the dispute only affecting England and Northern Ireland.
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."
Health staff picketing outside St Thomas' Hospital opposite Parliament in central London said they were determined to carry on taking action up to the general election if the deadlock is not broken.
Midwives stood alongside nurses, radiographers and other staff, blowing whistles and chanting: "What Do We Want? Fair Pay. When Do We Want It? Now!"
Bus, lorry and car drivers honked in support as they drove past, while cyclists stopped to pick up a sticker backing the strikers.
Unison's London regional secretary, Linda Perks, said the mood among her members was "very positive", predicting the dispute will run until next May unless there are fresh talks.
"This is not just about this year's pay because the Government's approach looks like being the same next year, which means 60% of staff will continue to be denied a pay rise.
"It's like a game of snakes and ladders because health workers will be back to pay levels of 2013, forcing them to work overtime or take out loans.
"The pay campaign will continue because we simply cannot afford to back off."
The GMB said the strike had been "rock solid".
Rachael Maskell, Unite's head of health, said over 120 picket lines had been mounted, with strong support from workers and a "swell" of public support.
"Our members have been especially grateful for all the messages of support they've received from the public. They see the unfairness of the Government's decision to deny NHS staff a decent cost-of-living pay increase after years of pay freezes."
NHS England said initial reports showed that of the 453,664 staff due to work at 8am this morning, 12,303 were absent on strike, which is 3% or one in 30, compared to 4.6% during last month's strike.
Midwives' overtime claims are costing more than giving them the recommended 1% pay award rejected by the Government said the Royal College of Midwives (RCM).
During the week of strike and further industrial action by NHS staff in October, RCM members claimed for overtime they would normally work for free. They recorded their overtime on timecards provided by the RCM.
With almost 500 responses and more still coming in, the results show that midwives worked an average of three hours overtime during that week.
Cathy Warwick, chief executive of the Royal College of Midwives, said: "This is an assault on the NHS pay system and on the independence and integrity of the Review Body.
"There is a lot of smoke and mirrors from the Government on this, trying to confuse the issue and confuse the public. The upshot is that in 2016 many of our members will be on the same pay as they were in 2013. This is not right or fair.
"I am asked how a 1% award is affordable. My response is that it is a question of priorities, of how this country wants to spend its money. If there is not enough money for the NHS, that is because the Government has decided to limit its budget. It is a political decision rather than an economic one."