Rugby fans could face significant increases in match ticket prices if controversial government plans to block satellite coverage come to fruition.

The Irish Rugby Football Union (IRFU) would not be drawn on the potential effects on fans but sources say it is entirely likely that supporters could pay the penalty for a loss in revenue.

"The fans could bear the brunt of the cost but that would not be the desire of the IRFU," a well-placed source said, adding that even significant price hikes on match tickets would fall far short of plugging the financial void.

Controversy surrounding minister Eamon Ryan's move to include Six Nations and Heineken Cup rugby on a list of protected 'free-to-air' sports culminated in an IRFU press conference last week in which the plans were derided.

It is understood both the IRFU and the Six Nations are seeking legal advice regarding a challenge to the move. However, it is highly unlikely that a domestic court action would be successful.

A High Court injunction blocking the minister's move could be granted only if it could be demonstrated that he did not adhere to due process, something he seems to be sticking rigidly to.

"In order to overturn a law that is in place, they would have to show some sort of flaw other than their disagreement," said Daithí Mac Síthigh, a lecturer in media law at the University of East Anglia. Even if they could secure an interim injunction, he said, there is probably no clear route to advance a legal objection.

The EU has to approve the final list and it is understood solicitors for the Six Nations may be examining potential avenues at European level.

"This is only of value to the IRFU because TV exists," said Edward McGarr, a solicitor specialising in media law. "They don't own the airwaves. All of the communications companies are licensed sooner or later in that they are dependent on national licences to operate."

Patrick Kinsella, a broadcast lecturer and head of journalism at Dublin City Uni­- versity said that, based on indications from American broadcasters, audience share is depleted by commercial TV.

"The signs from the US, where sport is huge, are that you don't see any big move of big sports to satellite because their experience is that the audience collapses," he said. "I suspect TV audiences for rugby would be smaller if people had to pay for it. It doesn't mean the revenue would necessarily be smaller."