NICOLA  Sturgeon will have the power to approve Police Scotland requests to spy on MSPs under new UK snooping legislation, the Prime Minister has confirmed.

The UK Government is writing the so-called Wilson Doctrine - the presumption against routine spying on parliamentarians - into law.

The Investigatory Powers Bill initially raised concerns that MSPs, MEPs and members of the Welsh and Northern Ireland assemblies would not enjoy the same protections as Westminster MPs.

But in a letter to Holyrood Presiding Officer, David Cameron said the present rules would continue to apply.

The Prime Minister will continue to have approval over the security services putting politicians under surveillance, including issuing warrants to access phone and email  communications.

He wrote: "The safeguards for all parliamentarians will be the same, with one exception: the Prime Minister will play no role should there ever be any proposal to conduct any such activity by Police Scotland, where these warrants are authorised by the Scottish Government.

"It would be up to the Scottish Government to decide how to handle any such case, should it ever arise."

His comments were welcomed by Ms Marwick and the Scottish Government.

A  Scottish Government spokeswoman said: "We welcome the Prime Minister’s confirmation that the so-called Wilson Doctrine will apply equally to MSPs and MPs.

"As part of our scrutiny of the Investigatory Power Bill, we will give careful consideration as to how similar provisions should be put in place for any warrants issued by Scottish Ministers for the purpose of preventing or detecting serious crime."

Under current laws Police Scotland can gain access to the emails and telephone records of members of the public on the approval of specially-trained senior officers.

The force requires Justice Secretary Michael Matheson to approve interception warrants, which allow officers to tap phone calls.

Last year, The Herald's sister paper, the Sunday Herald, revealed a rise in the number of approvals giving officers access to people's emails and telephone records.

More than 19,000 requests were approved in-house by senior officers, up five per cent from the previous year. Police Scotland refused to say how many times it asked the Scottish Government to approve  interception warrants.