Kerr said: "The other four unions are currently operating, or attempting to operate, anti-competitive practices. They have formed a cartel to exclude England and we think that what they are doing is illegal.
"Anti-competitive practice is against the law both in the UK and in the European Union. We are running businesses now and these guys [in the other four unions] just don't seem to understand that you cannot dictate, you can't operate cartels.
"I am sure if it goes much further we will be asking the Office of Fair Trading to have a look at what they doing.
"I think they have to recognise that the clubs are a beneficiary of the BSkyB agreement, and we feel we have to protect that situation. If they are trying to induce either Sky or the RFU to break the contract then we are entitled to damages.
"From our point of view, no other broadcaster is prepared to put money into club rugby. How are we supposed to get a professional sport off the ground if no money is going to come into it? We believe the other unions are on very dangerous ground. And if they go all the way and try to restrict contact between clubs, and all the other various levels, they could be in serious hot water."
The players are also beginning to show concern. Will Carling said: "English rugby cannot survive without the Five Nations. The Five Nations' Championship has to be saved. It has been the foundation for the northern hemisphere for years.
"We should have the Five Nations and we should add to that. We should be bringing in Italy and everyone else. I was in France 10 days ago and there were players from all the countries there and they were saying we have to play the Five Nations. They want England in it."
There were conciliatory noises from all four rival unions yesterday. France's president, Bernard Lapasset, said the door was still open to England, while the Scottish Rugby Union issued a statement welcoming the call by the new RFU president, John Richardson, for urgent talks. However, the SRU said the situation was "beyond the 11th hour", and the RFU must come to an agreement "in a matter of days rather than weeks" if they were to be reinstated.
To that end, Richardson last night issued a statement from Twickenham which opened the way for further talks.
It read: "I am pleased to note from the Scottish Rugby Union press statement that Scotland, Wales and Ireland have left the door open for further discussion. We are committed to, and value highly, the Five Nations' Championship.
"The RFU's principal aim is to ensure the future well-being of English rugby and we believe that this includes being part of the family of nations. On that basis we are prepared to meet the other nations and consider ideas consistent with that aim."
But the other four unions have insisted that until the matter is resolved England will remain in exile from the tournament.
Vernon Pugh, the Welsh Rugby Union chairman, said last night: "We have discussed the Four Nations' tournament with the BBC and they have given us assurances that they have no difficulty with it at all."
English players will be selected for the British Lions tour of South Africa next summer even if England do not participate in the Five Nations' Championships. Ray Williams, the chairman of the tours committee, confirmed that the selection process will involve all the British and Irish unions.Reuse content