Waiting lists for surgeries are soaring as senior doctors are refusing to take on extra work in order to protect their pensions.
NHS Providers said it was hearing from hospital trusts whose consultants and senior managers are declining shifts, which is having a massive impact on patient care.
Consultants are refusing to work beyond their planned hours after receiving higher tax bills, following new pension rules in 2016.
One hospital has seen numbers waiting for routine surgery increase by 50% since April, with staffing issues due to the pensions problem partly to blame.
NHS pensions changes in 2016 have impacted upon those earning more than £110,000 a year due to the introduction of a tapered annual allowance.
This is a taxation threshold which restricts the amount of pension growth individuals are allowed each year before tax charges apply.
It gradually reduces the allowance for those on high incomes, meaning they are more likely to suffer an annual tax charge on contributions and a lifetime allowance tax charge on their benefits.
The tapered annual allowance means that for every £2 of income above £150,000 a year, £1 of annual allowance is lost, the British Medical Association (BMA) says.
Health leaders say the rules mean the NHS’s most senior and experienced staff are being pushed to leave, work part-time or refuse extra shifts.
NHS Providers chief executive, Chris Hopson, said: "It has now become clear that the Government’s proposal to solve NHS pensions problems announced a month ago, whilst welcome, is insufficient.
"We were waiting to see if the proposal would work and it clearly hasn’t. Staff are voting with their feet."
He added: "To quote two examples we’ve heard just this week: A senior anaesthetist who worked 27 Saturdays last year to reduce waiting lists has now said he cannot afford to work any extra Saturday shifts this year because it would give him a large tax bill he cannot afford to pay.
"This is now an immediate, major problem for the NHS. Trust leaders are saying the impact is growing rapidly.
"We have multiple trusts telling us they are expecting a significant increase in the number of surgery cases they will have to delay, leaving patients in pain and risking their problems getting much worse."
A poll for the BMA earlier this year found that many doctors were being driven to cut hours and retire early.
Six out of 10 of the 4,000 consultants in England responding to the survey revealed early retirement plans, with many blaming the penalties caused by pensions arrangements.
Dr Rob Harwood, chairman of the BMA’s consultants committee, said: "For the first time, we are seeing hospital trusts publicly admitting there is a problem; hospital chief executives now acknowledging something the BMA has known for months - doctors are being forced to say no.
"No to extra shifts to reduce huge waiting lists, no to covering for staff shortages, and no to overtime weekend cover.
"Not because they want to, but because if they don’t, they face huge bills, created by the ludicrous pensions taxation rules that the Treasury is so far refusing to overhaul.
"This Government absolutely has to see sense and agree to a major overhaul of pension taxation before patient care is bereft of high-skilled experienced doctors and lives are lost."
A Department of Health and Social Care spokesman said: "We want to make NHS pensions more flexible for senior clinicians, in response to evidence that shows this issue is having an impact on retention.
"We will carefully consider all views on our proposals."