The abolition of car parking charges at Welsh hospitals has led to a row between Labour health ministers in Cardiff and London.
Most Welsh hospitals will have free parking from 2011
UK Health Minister Ben Bradshaw said it did not make sense to spend NHS money on "subsidising" car parks.
He spoke as the Department of Health (DoH) said the move went against the UK government's climate change strategy.
But Welsh Health Minister Edwina Hart said it was "putting patients first" and accused the DoH of "sour grapes".
Mr Bradshaw made his criticisms on Radio 4's PM programme after the Welsh Assembly Government confirmed that free parking will start at Welsh hospitals from 1 April.
The Welsh NHS Confederation has said the reforms would "inevitably" put pressure on NHS trusts, which collect more than £5m in car parking revenue.
Patients, staff and visitors will be able to park free at almost every NHS hospital in Wales by the end of 2011.
WHAT HAPPENS ELSEWHERE?
England - The government leaves it to local health chiefs to decide on policy, meaning charges are common with some hospitals levying up to £4 an hour
Scotland - Government has introduced a cap of £3 a day, although many hospitals charge less
Northern Ireland - Also left to local managers to decide, but a review of the policy is currently being carried out
It will make Wales the first area of the UK to scrap the charges. Some hospitals in England charge up to £4 an hour, although Scotland has limited it to £3 a day, and a review is under way in Northern Ireland.
But Mr Bradshaw said: "We don't think it makes sense to spend money that's currently being spent on patient care - getting people treated faster and better - on subsidising car parks.
"If that's what Scotland and Wales want to do, that's one of the joys of devolution.
"We're spending the money on improving patient care.
"In Wales, you have to wait much longer for your operation, you have to wait much longer in A&E [accident and emergency].
"You're not going to enjoy the extended GP opening hours that patients in England are soon going to be enjoying.
"Those are the priorities that we think the English patients are more interested in, rather than subsidising anyone who wants to park in a hospital car park for free."
Reform of hospital parking charges was part of the One Wales document which formed the basis of the coalition assembly government between Labour and Plaid Cymru after last year's assembly election.
Sources close to Ms Hart said she was relaxed about Mr Bradshaw's comments and would not be responding to them.
However, she issued an angry response to criticism from both the DoH and NHS Confederation.
The DoH said it had no plans to "force" hospitals in England "to subsidise their car parks with resources that could be used to improve and speed up patient care. It would also be contrary to the government's climate change objectives."
Ms Hart said: "The statement actually sounds like sour grapes from the Department of Health because they've been probably having a lot of flak because they haven't looked at these issues themselves."
The confederation said Welsh NHS trusts faced a "dilemma" of how to maintain a car parks service without affecting patient services.
Ms Hart said the money collected from car parking fees represented 0.17% of the total annual budget for Wales' NHS trusts and called on trust chairmen to raise their financial concerns with her directly.
She said: "I have to say about the NHS Confederation I think that perhaps I understand the patients' needs in Wales far better than they are in terms of commenting.
"I always think about the NHS Confed - weren't they the ones who negotiated the GP contract on behalf of the government? So I rest my case there, I think."
Welsh Conservative health spokesman Jonathan Morgan said he always thought health delivery in Wales was the worst in the UK and was "astounded to discover that a Labour minister at Westminster agrees with me".
"This issue demonstrates the extent of the worsening relationship between Labour in Wales under Rhodri Morgan and Labour at Westminster under Gordon Brown.
"It also shows the real fear among Labour that the state of the health service in Wales, though devolved, will dominate the next general election."