The Prime Minister has condemned the downgrading of 999 calls in the East of England - but claimed there had been no harm to patients.
Questioned on whether he was 'ashamed' of the East of England Ambulance Service Trust report this week by Labour MP Toby Perkins, Mr Cameron responded that the case should be put into context.
• Ambulance service investigates grading of 999 response times in long-delayed report
• Update: East of England ambulance service downgraded thousands of 999 calls
Mr Perkins, an MP for Chesterfield, told the House of Commons: 'Our ambulance trusts are under such pressure they are downgrading the calls of some of the sickest people in the country.'
He claimed 57 people had died while waiting for an ambulance. On Thursday, the East of England Ambulance Service Trust (EEAST) published a two-page summary of a much-delayed report into how and why more than 8,000 emergency calls were re-graded between December 2013 and February 2014.
The full report, which was released on Monday, details how a small group of staff downgraded thousands of calls, against Department of Health guidelines, without telling the board or management.
The ambulance report did not look at all 8,300 calls affected over the two months, when call codes were changed, because of 'the high number of incidents involved'
Responding in the weekly Prime Ministers question session in Parliament, Mr Cameron said: 'Clearly what happened in East Anglia was wrong, and the change was made without the knowledge of the Trust's board.
'As soon as it was found out the chief executive reversed the decision, and ordered an independent investigation, an investigation carried out by someone from outside the trust, and the investigation found there had been no harm to patients.
'It is important to put this in context.'
Mr Cameron also used the question to turn his fire on Labour leader Ed Miliband over accusations that he had told BBC journalists that he wanted to 'weaponise ' the National Health Service in the run up to the election.
The Prime Minister said: 'At the weekend the leader of the opposition was asked seven times if he had used the phrase that he wanted to weaponise the NHS, seven times he refused to answer the question. Everybody knows that he said those words and if he had a shred of decency in him he would get up and say he should not have used those words and apologise.'
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