The Government has been making "misleading" comments about controversial pension reforms, according to the British Medical Association (BMA).
As doctors up and down the country take part in industrial action for the first time in 37 years, the union spoke out to dispel "partial representations of the facts".
Andrew Lansley's claims that taxpayers subsidise £4 out of every £5 of doctors' pensions is false, the union said.
A spokesman said: "The NHS pension scheme does not work by building up a pension pot - staff working now pay for the pensions of NHS staff who are retired. The scheme currently brings in £2 billion more than it pays out - this money goes back to the Treasury."
The Health Secretary's remarks that a more generous deal for doctors would mean a less fair deal for NHS staff overall were also misleading, the union said.
The BMA spokesman added: "The spending envelope which the Government says NHS pension entitlements must now be funded within is an entirely arbitrary amount, set with no regard to the actual funding position of the NHS scheme or the 2008 reforms. Pitting one staff group against another to stay within this 'envelope' is a completely false proposition. Doctors rightly pay more than lower paid workers and we are not seeking to change that."
The union also rebuffed comments that the current pension scheme, which was agreed in 2008, is not financially sustainable.
"Under the 2008 reforms, doctors had already accepted that contributions may have to increase in the future to cover the cost of improving longevity," the spokesman said. "However, these increases were linked to a carefully constructed measurement of costs. Given that the amount being paid into the scheme currently exceeds the amount being paid out, there is no justification for further immediate increases."
Doctors' participation in the action has varied up and down the country. In some places up to a quarter of GP surgeries are affected by the action. But in other areas "only a handful" of doctors are taking part.
Across London, 90% of hospitals are working normally, an NHS London spokesman said. Hospitals in the capital have had to reschedule around 490 operations and reschedule 3,200 outpatient appointments. There are 17% of GP practices providing a reduced service as a result of the action.