Doctors will start voting today on whether to take their first industrial action since the 1970s, in a dramatic escalation of the bitter dispute over the Government's controversial pension reforms.
Ballot papers will be sent to 103,000 members of the British Medical Association (BMA), with the result due at the end of the month.
The BMA has ruled out a complete withdrawal of labour, but if they vote in favour, doctors would not undertake duties that could safely be postponed.
The last time doctors took industrial action was in 1975, when consultants suspended goodwill activities and worked to contract over a contractual dispute, and junior doctors worked to a 40-hour week because of dissatisfaction with the progress of contract negotiations.
The BMA argues that higher paid NHS staff already pay proportionately more for their pensions than most other public sector workers, a disparity which it said increased in April when their contributions rose, and which is set to increase again.
By 2014, some doctors will see deductions of 14.5% from their pay for their pensions, compared to 7.35% for senior civil servants on similar salaries, to receive similar pensions, said the BMA.
Doctors currently at the start of their careers would be hardest hit, having to pay hundreds of thousands of pounds extra - double what they would have paid - in lifetime pensions contributions, according to the association.
"The BMA is taking this step reluctantly. It has always said it would prefer to find a way forward through negotiation, and that industrial action is very much a last resort," said a statement.
"However, it believes the government has mishandled the situation by failing to enter into genuine negotiation on the further changes now being imposed on top of the 2008 negotiated reforms. BMA members overwhelmingly rejected the government's 'final offer' made in December 2011, with almost two thirds of the 46,000 doctors and medical students who responded to a survey saying they were prepared to take industrial action to pursue improvements to the offer.
"The BMA has continued to lobby the Department of Health and the Treasury to return to meaningful talks. But in February 2012, with no movement from the Government, and the strength of feeling among doctors very clear, BMA Council decided it had no alternative but to ballot on industrial action."
The BMA pointed out that under the government's plans, NHS staff will be required to work until the State Pension Age (set to rise to 68, and probably further in future) until they can draw a full pension, rather than 65 for those on the 2008 pension scheme.
If industrial goes ahead, the BMA said patient safety will be the over-riding priority. Any action would not involve a full withdrawal of labour and emergency care, or other care urgently needed by patients, would be provided.
Any action will take place for a 24-hour period initially, with its impact - particularly on patients - assessed before any further action was taken.
GP practices would remain open and fully staffed, so that they could see patients in need of urgent attention that day, but it would not be possible to book an advance appointment on or for the day of industrial action.
The ballot opens just days after another national strike by public sector workers, including civil servants and lecturers, over the pensions issue, and inclusion in the Queen's Speech of a Bill to take forward the reforms.
Dr Alan Robertson, chairman of the BMA's pension committee, said the association was "gravely concerned" that ministers were pushing ahead with the "unnecessary and unfair" changes.
"There is real anger amongst hard working doctors about the way they have been treated," he said.