The French Rugby Federation is on a collision course with clubs from the Aviva Premiership and Top 14 as the dispute over the future of the Heineken Cup continued to escalate.

Just hours after Premiership Rugby chief executive Mark McCafferty declared he expects Celtic and Italian teams to join the 'Rugby Champions Cup', the FFR responded with a strongly-worded statement backing European Rugby Cup.

Approval from the Rugby Football Union, FFR and International Rugby Union is required if the Anglo-French breakaway is to go ahead and any teams from the RaboDirect PRO12 participating will need the same support from their unions.

But on the eve of the launch in Paris of potentially the final Heineken Cup, the FFR released a statement indicating that approval would not be forthcoming from it.

"No meeting or international competition involving French clubs can be organised outside the framework of the FFR and without its prior agreement," the statement read.

"The FFR has always been and will remain a major player in the European cups organised by ERC and backs proposals to permit the continuity and development of these.

"If the FFR is in favour of an improvement in the European cups, their organisation can only be envisaged under the edict of the European federations which make up ERC.

"The statement released by the clubs appears therefore irrelevant and inappropriate."

"The FFR has always been and will remain a major player in the European cups organised by ERC"

European Rugby Cup appeared to be in full retreat earlier in the day as its appointment of an independent mediator was met with a statement of Anglo-French intent.

The gravity of the situation facing ERC was confirmed when McCafferty stated that sides from the PRO12 have been in contact over the possibility of joining the breakaway.

Premiership Rugby, in conjunction with its French equivalent Ligue Nationale de Rugby, plans to finalise the structural detail of the Rugby Champions Cup when it knows who will be involved.

"Before we can release more information we need to know over the next few weeks which other teams will be joining the competition," McCafferty said.

"Once we know the final, or close to final, numbers then we'll settle on the competition formats.

"Various people have approached us about the possibility of joining and we've indicated to them that we'll keep their names confidential.

"We've heard that other people want to be involved in European competitions, that's why we've left the door open and expect it to be more than an Anglo-French competition.

"Once people saw on September 10 that we would seek an alternative to the Heineken Cup, interest has been expressed in at least knowing exactly what will be involved."

McCafferty is confident of securing support from the RFU, but left the threat of legal action hanging in the air should it not be forthcoming.

"We're asking for the RFU's support against the background that there will be no ERC competition in which we're taking part at the end of the season. We need to put in place new competitions," McCafferty said.

"If that scenario occurs where the RFU oppose what we're doing, we'd have to look at their reasons for opposing it.

"You can't just say from a legal point of view 'we don't want it so we're not going to approve it', especially when there's a conflict of interests.

"We'll try to overcome the issues and then take it from there. We're asking for support. We'd expect that support."

The announcement of the Rugby Champions Cup underlines Anglo-French determination to press ahead with their own version of the Heineken Cup, which appears to be in its death throes despite the FFR's statement.

McCafferty revealed the new competition would be overseen by an "organising body of some sort - it doesn't need to be as big, unwieldy or institutionalised as ERC".

He denied ERC claims that the detail of its TV deal with BT Sport is shrouded in mystery - "the RFU know what's in it" - and said that the French clubs will only play in a competition involving their English counterparts.