The SPL board instigated the investigation during a board meeting today following claims surrounding the club's use of employee benefit trusts (EBTs) during Sir David Murray's reign.

Former Rangers director Hugh Adam, who left the club in 2002, alleged that some payments were not included in official contracts that were registered with the SPL.

The use of EBTs, from 2001-2010, was the subject of a tax tribunal in January, which could result in a £49million bill, although Rangers have defended their use of the offshore payments.

But whether they were legal or not in the eyes of the tax tribunal would not matter if the club had not disclosed the payments on the official contracts.

A statement from the league read: "The SPL board has instructed an investigation into the alleged non-disclosure to the SPL of payments made by or on behalf of Rangers FC to players since 1 July 1998."

SPL rules prohibit payments to players that are not made "in accordance with a form of contract approved by the SPL".

Chief executive Neil Doncaster would not make any prediction on how long the investigation would take or which of 18 sanctions Rangers might face if found guilty.

Doncaster told Sky Sports News: "First we have to establish whether there were any payments that were made that were undisclosed at the time and, if they were, we will take that forward."

The Scottish Football Association confirmed on Friday they would investigate the allegations made by Adam.

The SFA had already launched an independent inquiry into recent events at Rangers after the club went into administration over unpaid tax bills last month, and specifically whether they broke rules regarding whether majority shareholder Craig Whyte was a "fit and proper" club official.

The SPL board meeting followed a general meeting where representatives from the 12 clubs discussed rules on financial fair play following Rangers' descent into administration.

Rangers were automatically deducted 10 points when they went into administration on February 14 but clubs today pondered whether the rules were fair and also the consequences should Rangers go into liquidation and emerge as a new company.

Dunfermline chairman John Yorkston said he would be uncomfortable with a 'newco' Rangers automatically taking their place in the SPL should the current club go into liquidation.

Yorkston told reporters: "As we speak today, if they come out of administration I personally feel it's a clean-slate job.

"If it's liquidation, it's a completely different kettle of fish.

"Liquidation is a completely different situation and they may well have to go down to the Third Division.

"We would have to look at it and see what all the facts are."

St Johnstone chairman Steve Brown would not address that specific issue but is a supporter of points deductions for clubs who are forced into insolvency scenarios.

"We try to run the club the proper way," Brown said.

"Other clubs have been allowed to refinance and I wouldn't say it annoys me, it's just unfortunately part of the game.

"We've run the club with no debt but unfortunately won no trophies, so until such times when you are rewarded for not going into debt then it's not going to change."

However, other SPL chairmen admitted they would consider the wider impact on Scottish football should a new Rangers emerge.

Kilmarnock chairman Michael Johnston said: "There are certainly commercial considerations at play here.

"There is no underestimating the value of Rangers and Celtic to the SPL and Scottish football in general so I think it would be foolish to overlook the commercial aspects of this for all the other clubs."

St Mirren chairman Stewart Gilmour said: "Scottish football needs a strong Rangers and Celtic, that's my personal view.

"But once we see what the whole position is, we as a club can make a decision from there.

"We try not to jump in off the cuff, I don't think it's the time for that. None of us really know what's happening with Rangers.

"It's a very difficult time for Rangers Football Club and the players and management. It's for their house to get sorted out.

"But I think in many ways it's better we all leave them to get sorted out, see where they are and then we can come to some decision."