The prime minister holds a news conference once a month Watch the briefing

The health secretary sparked anger after saying the NHS was having its "best year" despite huge job losses.

The premier urged a sense of balance about Labour's NHS record saying there had been great improvements since 1997.

He used his monthly news conference to stress increased numbers of nurses, better cancer and heart treatment and an end to the annual "winter crisis".

'Mismanagement'

He also defended Ms Hewitt's comment that the NHS was enjoying its "best year ever".

"She didn't just say this," he said.

If the prime minister is right in his assertion that things have massively improved since 1997, he has nothing to worry about Analysis: Blair NHS clash

"She said it because waiting lists have never been lower since the health service records began, accident and emergency improvement has dramatically improved in the last few years, cancer and cardiac care are the best they've been in the NHS, and we have record numbers of extra doctors and nurses. These are facts."

Conservative leader David Cameron weighed in to argue that the problem with the NHS was not reforms, but "mismanagement".

Asked about Ms Hewitt's comments, he said: "I just wonder what planet she is on.

"We've got 9,000 people in the health services faced with job cuts already."

Strike threat?

Liberal Democrat health spokesman Steve Webb said: "This is crisis management - the government is trying to sort out the problems of decades in weeks."

The exchanges follow a warning by Unison general secretary Dave Prentis that job losses in the NHS could spark industrial action.

That prompted Mr Blair to say: "We have a tremendous challenge, every health service in the world does. No-one is pretending the NHS is without real challenges and problems."

But he called for recognition that although his NHS reforms were difficult they would ultimately result in the more efficient use of resources.

Mr Blair meanwhile brushed off a question about "Dave the Chameleon", the cartoon character designed to lampoon Mr Cameron in Labour's local election broadcast, saying he thought the Tory leader could take it.

But Mr Blair added: "At some point he is going to have to make some tough political decisions ... but that time has not yet come."

Retirement

The prime minister was also asked about pay equality, and the fact his minister for women is unpaid. He said it was an issue that "certainly needed to be resolved".

On press rumours he has changed his mind on Lords reform and now backed a "democratic" upper house, he said he would comment in due course.

Mr Blair was also asked about the premature retirement of Newcastle United centre forward Alan Shearer and whether there were "any parallels with another North East icon" - a light-hearted reference to the prime minister who has a constituency in County Durham.

Told the footballer had injured his knee, Mr Blair retorted to laughter: "Knees? There is nothing at all wrong with my knees."