David Cameron was facing fresh questions about his election guru Lynton Crosby after it emerged the lobbyist's firm advised a private health alliance at the time of the Government's controversial NHS reforms.
The Australian strategist's Crosby Textor firm advised an umbrella group of private healthcare providers on how to exploit perceived "failings" in the NHS, according to a leaked document obtained by The Guardian.
The newspaper published extracts from a slideshow presentation produced for the H5 Private Healthcare Alliance, which stated that people believe the NHS provides good healthcare, though they believe it was "too bureaucratic with long waiting lists".
Crosby Textor advised its client that 63% of those questioned in a poll conducted for the presentation believed that "going private frees up the NHS waiting list".
Although the lobbying links pre-dated Mr Cameron hiring Mr Crosby, shadow health secretary Andy Burnham claimed there was a "shocking conflict of interest" at the heart of his administration.
The Guardian said the presentation was made by Crosby Textor, known as CTF Partners in Britain, towards the end of 2010, just months before the Health and Social Care Bill was given its second reading in the House of Commons in January 2011.
Crosby, who masterminded the Tories' 2005 election campaign, was brought back into Conservative HQ by the Prime Minister in November last year, and Labour claimed his return coincided with a fresh push for private sector involvement in the NHS.
Burnham said: "The more we learn of Lynton Crosby's business dealings, the greater the number of question marks left hanging over the conduct and integrity of David Cameron's government.
"It simply cannot be right to have people paid to lobby for private health organisations wandering round Downing Street when policies are being discussed that could benefit their clients. It is more evidence of a shocking conflict of interest that David Cameron has created at the heart of his Government.
"Shortly after Lynton Crosby started work for the Conservative Party, the Government shifted its position in favour of private health companies by trying to sneak NHS regulations through the House forcing services out to the market. At the time, experts expressed surprise at the sudden shift in position. Now we can guess why.
"Once again, it is more proof that you can't trust David Cameron with the NHS."
Cameron has insisted that Crosby had not intervened in policy decisions, but has repeatedly refused to answer questions about the extent of his conversations with the lobbyist.
The Prime Minister has come under sustained pressure to say whether Mr Crosby, whose lobbying company has also worked for tobacco giant Philip Morris, had spoken to him about shelving the plan for cigarettes to be sold in plain packaging.
Cameron, appearing on BBC1's Andrew Marr Show, claimed it was a "media invention" and a "red herring" to suggest that Mr Crosby had any involvement in the decision.
Asked a second and third time if he had talked to Mr Crosby about the policy, Mr Cameron again stuck to the line that the Australian lobbyist had not intervened.
Marr said that was "not quite an answer to the question I asked", but the Prime Minister told him: "Well, that's the answer that you are getting."
Responding to the latest claims a Conservative spokesman said: "The Prime Minister has been clear that Lynton Crosby has never lobbied him on anything. Lynton Crosby is an adviser to the Conservative Party. He does not advise on government policy."