Labour leader Ed Miliband has acknowledged that the NHS in Wales has "big challenges to meet", but insisted that the Tories could not be trusted to run the health service.
The Conservatives have sought to highlight problems in the Welsh NHS, which is the responsibility of the Labour administration in Cardiff Bay, as a way of attacking Mr Miliband's party's record on public spending and running services.
First Minister Carwyn Jones admitted there had been "unacceptable" examples of poor care in Wales, but accused the Tories of "willing" a crisis in the country's NHS on a daily basis.
Health Secretary Jeremy Hunt and his Welsh counterpart Mark Drakeford have been embroiled in a cross-border spat about the NHS, and David Cameron has frequently highlighted the situation in Wales at Prime Minister's Questions.
In his keynote speech a the Welsh Labour conference, Mr Miliband said the challenges facing the NHS in Wales included "better, early diagnosis and support for the older population".
He claimed the Prime Minister was keen to highlight issues in Wales to avoid discussing the impact of the coalition Government's controversial health reforms in England.
"But when David Cameron talks about the NHS in Wales, let's remember what the NHS in Wales was like when the Tories were last in charge," he said.
"There were half the A&E consultants you have today. The number of nurses was being savagely cut back.
"And the Tories set a target for people to get treatment within 18 months. But couldn't even deliver on that.
"And why is David Cameron so desperate to talk about the NHS in Wales?"
"Let's remember the real reason: It's because he doesn't want to talk about what he is doing in England.
"Billions wasted on a top-down reorganisation that nobody wanted and nobody voted for. A top-down reorganisation in the NHS he promised would not happen."
Mr Miliband said in England thousands of nurses had been laid off, while managers were pocketing redundancy payments before being rehired.
He said: "T hese are the reasons why, whatever the pressures and challenges you face here, nobody in Wales is saying: 'Please send for Cameron'.
"The people of Wales know the oldest truth in politics: y ou can't trust the Tories with the NHS."
At the conference in Llandudno, Mr Miliband promised greater powers for the Senedd if he is prime minister after 2015
The next Labour government will pass a new Government of Wales Act, w ith powers assumed as devolved to Wales unless specifically reserved to Westminster.
The move would bring Wales into line with Scotland, "m odernising and advancing the devolution settlement for generations to come".
Mr Jones - who hit out at a "Tory war on Wales" - acknowledged there were some "difficult truths" about the NHS in Wales, including "examples of poor care, which are unacceptable".
He said there are waiting times for diagnostic tests which are "too long, for too many", examples of "complacency "at the top of local health boards and a "complicated complaints system".
"For those failings, we hold up our hands and say, yes we could have done better. And we will do better," he said.
"But, even with all those challenges facing us, isn't the most fundamental truth about the NHS that, like democracy, will always be the best imperfect solution we will ever have."
Highlighting problems in England he added: " Make no mistake; all our health services face pressure - in England, Scotland, Northern Ireland and Wales. As they have done, in one way or another, in every year since 1948.
"Unlike the Tories though, we take no pleasure in these sorts of statistics.
"Unlike the Tories in Westminster, we want the NHS in Wales and England to thrive.
"The truth is - we will not talk the NHS down. The same cannot be said of the Prime Minister.
"The Tories aren't warning people in Wales about a crisis in the health service; they are willing it to happen on a daily basis.
"That is the sort of Government that exists in Whitehall. And that is why they must be defeated."