THE tax office has been criticised after saying it cannot give the cost of its five-year chase of ­Rangers in one of the biggest tax claims it has ever pursued.

Her Majesty's Revenue & Customs has said it would cost too much to find out the costs.

The development has been described as "extraordinary" by Rangers fan groups which have accused HMRC of wasting public money in its "witch-hunt" in pursuit of a "phantom tax debt".

HMRC has confirmed it will contest the decision of an upper-tier tax tribunal to uphold an earlier ruling on what is known as the Big Tax Case.

That ruling said Rangers' use of employee benefit trust (EBT) loans to players and other staff was legal, and payments were not taxable, as Sir David Murray's Murray International Holdings, which formerly owned Rangers, has maintained.

But the tax office is known to want to pursue the club as a matter of principle, and there is a ­procedural hearing on its latest appeal on February 3.

Many believe fear of the tax case led to Lloyds Banking Group ­insisting £18 million in club debts were cleared, leading to the sale to Craig Whyte, liquidation, and eventually Rangers playing in the bottom tier of the Scottish Football League.

If a fresh HMRC appeal succeeds, it will have no bearing on today's Rangers but fans have called for a Government inquiry into HMRC's handling of the case.

Chris Graham, of the Union of Fans, the Rangers supporters ­coalition, said of the HMRC response to queries over the case's cost: "This is extraordinary. Lawyers are ­meticulous about things like that, they clock all the time they spend on a particular client.

"There are question marks over why they are continuing to pursue this when we know they have been offered to settle."

When asked what the costs were to date of pursuing the tax case HMRC, a representative said: "HMRC holds information that falls within the scope of your request. However, we estimate that it would exceed the FOIA (Freedom of Information Act) cost limit to deal with it."

That limit, he said, was the cost of one person working for three-and-a-half days. He added: "Normally, HMRC would explore with you how you might be able to narrow or refine your request so that it did not exceed the FOIA cost limit. However, in this case, I cannot see any scope for doing this.

"Even if we had been able to find and extract all the information in the scope of your request, we would never release anything which could be linked to an identifiable person; be that an individual, company or any other entity."

HMRC says EBTs were used by more than 5000 UK firms, including football clubs in England. The Rangers case was seen as a way for the tax office to claw back many millions of pounds from their use.