The Government is understood to be willing to upgrade its investigation into the Olympics ticket controversy to a statutory inquiry if witnesses refuse to co-operate with the inquiry it is in the process of setting up.

Minister for Sport Shane Ross is to announce the terms of reference for a non-statutory inquiry on Wednesday. Such an inquiry does not have the power to compel witnesses to attend.

It is understood a clause is to be included in the terms of reference which would allow for the investigation to develop into a statutory inquiry if necessary. This would give it the power to compel witnesses and demand documents if the relevant bodies declined to co-operate.

It is expected the terms of reference will date back to 2010 when the THG group was first awarded the Olympic Council of Ireland (OCI) contract for ticket sales for the 2012 London Games.

Mr Ross will on Wednesday announce the structure of the Government inquiry, with the investigation to be chaired by a retired member of the judiciary. It will be given 12 weeks to complete its work.

Mr Ross met Fianna Fáil spokesman on sport Robert Troy on Tuesday who sought a series of amendments to the draft terms of reference produced by the Minister. Mr Troy requested that the inquiry specifically examine how the Pro10 agency secured the contract to handle tickets allocated to the OCI for the Rio Games.

The Fianna Fáil TD also asked that the relationship between Pro10 and UK company THG be examined by the inquiry.

Pro10 and THG have both said they will co-operate with the inquiry.

The ticket controversy developed after a Dublin man working for THG was arrested in Rio on August 5th and tickets seized, many of them coming from the Olympic Council of Ireland allocation.

Mr Troy said: “Fianna Fail’s main request is that there are mechanisms available to develop this into a statutory inquiry if witnesses do not co-operate.

“But the whole area of corporate governance and administration around the allocation of Olympic tickets, the athletes, their families and the general public have to be to the forefront generally.

“The wider issue is overall ticket governance and the specific issue centres in Rio and London. The purpose of the inquiry is to ensure this never happens again.”

The terms of reference will allow the judge to examine as far back as the 2012 Olympic games and to examine corporate governance at the OCI.

Meanwhile, Minister for Agriculture Michael Creed has called on Football Association of Ireland chief executive John Delaney to make a public statement on the controversy. Mr Delaney is also vice-president of the OCI.

Mr Delaney was one of six people named on a warrant issued on Saturday by a Rio court authorising the seizure of their passports. Three of the six are still in Rio. Mr Delaney did not travel to Rio for the Games.

Mr Creed said it was “incumbent on all parties” to co-operate with the Government’s inquiry, including Mr Delaney.

“I think there’s an obligation on anybody. In the context of a non-statutory inquiry, there isn’t compellability.

“But, it is incumbent on all parties – and the OCI are saying they will co-operate – and John Delaney, not only as chief executive of the FAI, but also as an OCI member, has to live up to the spirit of that OCI commitment now that they will co-operate.

“And therefore we would like to hear from all parties, including Mr Delaney.”