Opposition parties were last night keeping the pressure on Alex Salmond over his ties with Rupert Murdoch.

Scottish Labour leader Johann Lamont challenged him to produce documentary evidence that his conversations with the media mogul were about jobs in Scotland and not about seeking support for the SNP.

She has written to the First Minister calling for him to reveal details of meetings with Ministers and external agencies that could prove he was genuinely concerned about securing jobs and not the backing of the Murdoch-owned press.

Mr Salmond said he spoke to Mr Murdoch about the proposed News Corporation takeover of BSkyB, but said it was about concerns over 6000 Scottish jobs.

Yesterday, Deputy First Minister Nicola Sturgeon, denied there was any link between the discussions over the bid and the later decision by the Scottish Sun to support the SNP.

Ms Sturgeon insisted there was no deal to back the bid in return for editorial support.

She said: "I am emphatically and unequivocally saying there is no connection between these two things."

Opponents, however, are refusing to back down, and want Mr Salmond to release details of discussions with his Enterprise Minister, Scottish Enterprise and details of any Cabinet discussions on the issue.

Ms Lamont said there are six questions the First Minister must answer, including whether the First Minister believes jobs have now been put at risk as a result of the withdrawal of the News Corporation bid.

She also demands to know if Scottish Enterprise was asked to look at what assistance it could offer News Corporation to base further jobs in Scotland if the company was successful in its takeover bid of BSkyB?

She said: "At the moment, the First Minister appears to have taken Rupert Murdoch's word for it that this takeover would be good for Scotland.

"Given the sensitivities around this takeover, and the potential impact on Scottish jobs that the First Minister claims, it is unthinkable that he gave it his backing without any discussions with his Cabinet, his enterprise agencies and without any economic impact assessment being drawn up.

"The First Minister must disclose any evidence the takeover would be good for jobs, otherwise public confidence in his handling of the Murdoch affair will continue to plummet."

On a visit to Glasgow yesterday, Labour leader, Ed Miliband said the First Minister was an "undercover lobbyist for Rupert Murdoch".

Mr Miliband said: "I think the revelations are shocking. The First Minister has questions to answer. If it is about a campaign to bring jobs to Glasgow why wasn't he open about it. What he actually did was act as an undercover lobbyist for Rupert Murdoch."

Asked if he would welcome an endorsement from Mr Murdoch before the next election Mr Miliband said he would be "happy" but turned it back to the First Minister.

He said: "They make their own decisions about what they want to do and who they want to back. If people want to back me and the Labour Party I am happy that they do.

"Alex Salmond was the guy who after Milly Dowler didn't call for a judicial inquiry or want to stop the BskyB bid. Instead, he invited them round for tea."

Liberal Democrat leader Willie Rennie called on Mr Salmond to release private emails with special advisers.

He said: "Following the revelations that the SNP Government failed to disclose a meeting between the First Minister and Rupert Murdoch in New York in 2008, it is clear we need full transparency."

He added: "The First Minister should release his private correspondence with his special advisers. The suspicion that Mr Salmond traded Government influence for political support will not fade until we see the full picture."

Responding to Mr Miliband's comments, Ms Sturgeon said: "This is rank hypocrisy from Ed Miliband, given his own attempts to curry favour with News International. It is a desperate bid by Labour to divert attention from Johann Lamont's blunder at First Minister's Questions, where she appeared to be completely clueless about a major recent jobs announcement in Glasgow."