POLICE are investigating the circumstances surrounding Charles Green's takeover of Rangers.

It was confirmed last night that they are to probe the background to Mr Green's Sevco consortium buying the club's assets, for £5.5 million in 2012.

The move follows a separate inquiry into Craig Whyte's alleged fraudulent takeover in May 2011.

Four men have appeared in court charged with fraudulent activity three years ago.

And an arrest warrant has been issued for Whyte. Last night a source insisted he would return from abroad to fight the case against him.

Whyte continues to claim he was the man behind the Sevco 5088 consortium that bought the liquidated assets of Rangers and that front man Mr Green was in cahoots with him.

Whyte has launched legal action that raises questions about the current ownership of the club, alleging that a transfer of assets from Sevco 5088 Limited to Sevco Scotland Limited was illegal.

Club auditors Deloitte previously raised concerns over an "uncertain outcome" of Whyte's potential litigation which they said remains a key uncertainty hanging over the business.

Rangers have consistently said Whyte's claims have no merit.

Whyte is abroad but an informed source close to him has revealed he is expected to return. Three of the four who appeared at Glasgow Sheriff Court on Monday accused of fraudulent activity are David Grier, Paul Clark and David Whitehouse.

They worked with Duff & Phelps, the company appointed administrators after the Rangers operating company fell into insolvency under the reign of Whyte from May 6, 2011, to February 14, 2012. They also negotiated the purchase by Mr Green's consortium.

A report sent to the procurator fiscal in Glasgow over the Whyte affair before the detentions related to alleged "incidents" between January 2010 and November 2012.

That period covers more than a year before Whyte took the reins at Rangers but also up to five months after Mr Green's consortium bought the assets.

A police source said there is an ongoing probe into the Sevco takeover that is now being handled separately from the Whyte inquiry.

The insider said: "There is still an ongoing inquiry in respect of other things that went on and there may well be other individuals involved."

A source who has been in regular touch with Whyte said he would be surprised if he did not return to fight the allegations.

"He will be defending it. I would imagine he would plead not guilty but he has not seen the allegations on the petition yet," said the source. "I think they [the police] are bound to be looking at the Charles Green takeover too."

Whyte and business partner Aiden Earley have been locked in a legal battle which is central to the ownership of the Rangers.

Sevco 5088 was the company identified by administrators on May 29, 2012, as being the newco that was "contractually obliged" to purchase the assets and business of former operating company RFC 2012 plc.

Mr Green denied last year that Mr Whyte or Mr Earley were involved in Sevco 5088.

He said director documents lodged at Companies House were not valid and it is understood they were referred to police by legal firm Pinsent Masons. The forms were dated May 9, 2012, three days before Duff & Phelps signed an offer letter and granted Sevco 5088 exclusivity to complete a takeover.

Mr Green admitted teaming up with Whyte in the early stages of his buyout but claimed he was fed information he wanted to hear in order to secure his shares.