By Ian Dunt Follow @IanDunt
The prime minister's role in deciding Andy Coulson's security clearance must be made public or he will face a loss of public trust, Labour has said.
After a day of questions about why the former Downing Street director of communications was not given a thorough background check, Labour issued the demand to David Cameron and Cabinet secretary Gus O' Donnell.
"There are now very serious questions that the Cabinet secretary must answer about the vetting of Andy Coulson," said shadow media secretary Ivan Lewis.
"Mr Coulson was in the most senior communications job in government but was not subject to the vetting levels of his predecessors.
"Sir Gus O'Donnell must explain what role he played in this decision, and what role the prime minister played in it. This must be cleared up to remove any suspicion that Mr Coulson was exempted from high level vetting because of fears that he would have failed it."
The pressure on No.10 increased significantly yesterday after it was revealed that Mr Coulson's successor, former BBC executive Craig Oliver, underwent full security clearance, as did Gabby Bertin, his deputy.
Critics have been incensed by the prime minister's reluctance to address the issue. Despite being asked to name the firm which vetted Mr Coulson several times in the Commons, he refused to do so.
A string of former Downing Street press advisers went on record saying they were perplexed as to how Mr Coulson could do his job properly with such a low security clearance.
Many observers believe Mr Coulson was spared the vetting procedure because it could have revealed that he knew about alleged widespread phone-hacking at the News of the World.
"There was something very odd going on here," former Downing Street director of communications Alastair Campbell wrote on his blog yesterday.
"It would be wrong to say it would be impossible to do the job without access to sensitive material for which DV [developed vetting level] status is required. But it would certainly be a lot harder.
"I suspect that in coming days journalists will quite easily be able to ferret out information to the effect that Mr Coulson had been at meetings and seen papers he was not, apparently, cleared to see."
Lance Price, another press adviser to Tony Blair, also said he struggled to understand how Mr Coulson would have been able to do his job properly without higher clearance.
Full security clearance sees Ministry of Defence officials conduct rigorous checks on an individual's background and history, including their personal life, financial situation and debts.
The development comes amid reports from Reuters saying that Mr Coulson knew about bribes to the Met from News International.