The First Minister has been criticised over a phone conversation with scandal-hit media mogul Rupert Murdoch to discuss the tycoon's new weekly newspaper.

The call followed an apparent expression of support for independence from the News Corporation chairman on social networking site Twitter.

On Monday, Mr Murdoch tweeted: "Let Scotland go and compete. Everyone would win."

A spokesman for the First Minister said Mr Salmond called Mr Murdoch on Tuesday to discuss new paper The Sun on Sunday, and said they also talked about the tweet.

Mr Salmond said: "It was an interesting eight words: a textbook example of how to deploy a tweet and cause a great stir.

"We are in a debate in Scotland and internationally about Scotland's future, and I welcome all contributions to the debate, including Mr Murdoch's."

The tycoon's words followed a message on the social networking site on Sunday in which he said: "Alex Salmond clearly most brilliant politician in U.K. Gave Cameron back of his hand this week. Loved by Scots."

But Scottish Liberal Democrat leader Willie Rennie MSP said the First Minister had a duty to use the call to ask Mr Murdoch about the alleged criminal activities of journalists employed by News Corporation.

He said: "I think we need to know whether Alex Salmond put the difficult questions to Rupert Murdoch. Did they cover the Leveson inquiry, phone hacking and Murdoch's oversight of The Sun and the News of the World?

"The First Minister has responsibility to serve the wishes of the country first, rather than the narrow interests of his party."

Crisis

Mr Murdoch's News Corporation is the parent company of News International, which publishes The Sun and The Times newspapers. It also published the News of the World before that paper closed down following allegations of hacking voicemail messages left on the phone of murdered teenager Millie Dowler.

The Sun switched from opposition to the SNP before the 2007 election to support for the party at the election last May.

The spokesman for Mr Salmond said the editorial stances of News International newspapers were not discussed in the phone call.

In August 2011 the Scottish Government published letters between Mr Salmond and Mr Murdoch, which show attempts to bring Mr Murdoch to Scotland as the guest of honour at the Gathering, a cultural celebration intended as the centrepiece of the Year of Homecoming.

The First Minister suggested it would be a great spectacle for coverage by Murdoch-owned Sky television.

An invitation was also extended to Mr Murdoch for him to join Mr Salmond at a golf event in Kentucky in the US.

In another letter, Mr Salmond offered the tycoon tickets for a performance of the Black Watch play in New York.

The letters came with a list of dates and names covering meetings held with editors, journalists and other executives stretching back to June 2007, shortly after the SNP first took office.

Mr Murdoch is in the UK to take charge of the latest crisis involving one of his titles, following the arrest of several senior journalists at The Sun.

He announced he will publish The Sun on Sunday for the first time this weekend.