The tax bill that crisis-hit Rangers are facing is around £6m higher than previously thought.

Last week administrators Duff and Phelps were called in after HM Revenue and Customs tried to get court appointed insolvency experts in to the Ibrox club.

At the time, the administrators said unpaid PAYE and VAT worth around £9m had been deducted from employees’ wages, but was not handed over the HMRC, which had prompted the Court of Session move.

STV understands that the unpaid tax is closer to £15m and has increased as administrators have started looking over the financial arrangements at the Ibrox club since Craig Whyte took over last May.

The £15m total is believed to include both the £9m dating back to the takeover last May and the outstanding 'wee tax case' between Rangers and the government authority. Mr Whyte claimed that £4.4m of the total owed to HMRC was in relation to the ‘wee' case.

Previously, joint administrator David Whitehouse said: “Unpaid taxes are not appropriate long-term funding for the club."