Lothian and Borders Police is to investigate allegations of perjury during the Tommy Sheridan defamation case.
The News of the World claimed at the weekend that it has a tape which proved Sheridan lied during the case in which the former leader of the Scottish Socialist Party won £200,000 in damages against the paper.
A Crown Office spokesman said it was not possible to speculate on the timescale for the investigation.
The spokesman said: "On the basis of information presently available to her the procurator fiscal at Edinburgh has instructed police to begin a criminal investigation into allegations of perjury. Lothian and Borders Police will submit a report to the procurator fiscal in due course."
Sheridan told BBC Scotland that the Crown Office was "only doing its job", but claimed: "It is a rehashed announcement from six weeks ago, there's nothing new." He said he would be happy to take part in any aspect of the police investigation.