The Rugby Football Union will sue Premier Rugby if the English clubs pull out of next season's Heineken Cup. The 12 Premiership clubs have voted unanimously to withdraw from the competition if their French counterparts carry out a threat to boycott the tournament.
Premier Rugby - the clubs' umbrella body - argue the Heineken Cup would not be a genuine European competition without the French teams. But RFU management board chairman Martyn Thomas insists the clubs are contracted to participate in the Heineken Cup and confirmed Twickenham would pursue legal action against them if they refuse.
Thomas told BBC Radio this morning: "We have a contract with our clubs which we signed in 2001 and in relation to Europe it is very simple. It says the clubs will compete in the European Cup or the European Shield. That lasts until 2007 so I am at a loss to understand their statement last night that they believe they can pull out."
Asked whether the RFU would have to sue Premier Rugby, Thomas added: "Regrettably that would be the case. Unfortunately again it is a situation of rugby having to resort to the courts."
The Ligue Nationale de Rugby, which represents the top 14 French sides, is likely to decide by Thursday whether or not to walk away.
Concern at the RFU's refusal to hand over share and voting rights - plus anxiety over fixture congestion next season, which starts with the Rugby World Cup - are behind the militant French stance.
Thomas remains hopeful an agreement can be reached but Premier Rugby chief executive Mark McCafferty is less optimistic.
"I'm going to continue to find a way to pull the French clubs back in but today the prospect of that, when the French clubs decide on Thursday, doesn't look great," he said.