RANGERS face fresh questions over their ownership after an investment company linked to disgraced former owner Craig Whyte said it would continue staking a legal claim over its business and assets.

The latest twist in Rangers' troubles came as a client of BNP Paribas Arbitrage SNC, the asset management wing of France's largest bank, became one of the club's big six shareholders by taking a 5.23 per cent stake.

The anonymous buyer has purchased 4.265 million shares sold by London-based investment managers Hargreave Hale.

It came on the day fans accused the Rangers board of being "incompetent" after it emerged certificates signed by former chief executive Charles Green and director Brian Stockbridge had been sent to shareholders involved in the recent open offer.

Union of Fans spokesman Chris Graham said: "It does not come as a huge surprise that this has not been done properly along with pretty much every other piece of governance within the club."

The legal action by Worthington Group, which has been connected to Whyte, appeared to disappear when the Financial Conduct Authority suspended trading in its shares at the company's request over a year ago.

But the ban was lifted over four weeks ago and now its chief executive Doug Ware has confirmed that the Rangers court case is back on the agenda.

It comes one year after auditors Deloitte flagged up the legal battle over ownership, saying it was a key uncertainty hanging over the Ibrox business. Rangers have consistently said Whyte's claims have no merit.

The case revolves around Whyte's allegations that Mr Green had acted as a "front man" for him to take control of the club - through the Sevco 5088 consortium that bought the liquidated assets of Rangers oldco RFC 2012 plc. Last year it emerged Worthington Group had 26 per cent of Law Financial Ltd, then one of Mr Whyte's companies and one which claims to have Sevco 5088 as one of its subsidiaries.

Included among Law Financial's assets was the legal action instigated by Whyte against Mr Green for the claim on Rangers' assets.

Mr Ware said yesterday: "Rangers litigation is a small and reducing part of our rapidly expanding investment portfolio.

"That said, the litigation will take its course and we'll have to see where it ends up, it's not on top of my agenda."

On Tuesday Whyte was barred from being a company director in the UK for 15 years. He has always insisted he was the main driver behind Sevco 5088.

Rangers assets were bought for £5.5 million in June 2012 and were transferred to a different company called Sevco Scotland, which then became The Rangers Football Club.

Whyte's main argument is that the transfer was illegal and Sevco 5088 remained the rightful owner of the club's assets.

Rangers said last night that their position remains the same as in May last year when it said it was preparing a "robust response" and that as legal proceedings were threatened it would not be appropriate to make public any further.

Mr Green has always denied he had ever been a "front man" for Mr Whyte.