The Rugby Football Union said last night it would not give in to blackmail after being cited as the main reason for the decision of France's 14 first division clubs to boycott the Heineken and European Challenge Cups next season.

The French Rugby Federation pleaded with the RFU to reconsider its position after Serge Blanco, the president of the French League (LNR), said that the clubs were pulling out of Europe next season largely because of the refusal of the RFU to hand over share and voting rights to its clubs, a stand which had delayed the signing of a new tournament accord. Blanco also admitted that fixture congestion in World Cup year had been a factor.

"Blanco is wrong to say that we went back on our word in refusing to hand over the rights," said the RFU's management board chairman, Martyn Thomas. "The minutes of the meeting are clear: we agreed to consider the position regarding shareholding and voting as part of an agreement with the clubs on the issues facing the game in England.

"We are not going to be blackmailed, and just as we would not interfere in France's domestic game, we have to be allowed to get on with our own affairs."

The French union pointedly said in a statement yesterday: "The persistent conflict between the RFU and its clubs is the reason for the boycott and the stable relations we have established with LNR is an example of how difficulties can be replaced by solidity. We urge everyone involved to appreciate their responsibilities and take the appropriate measures."

The RFU and Premier Rugby meet tomorrow, but Thomas expects progress to be slow. "I feel that the main reason behind the French clubs' decision is that they feel their league will be undermined by the World Cup. They are having to play a number of matches in midweek and they will not suffer financially by withdrawing from Europe for a season because they are being given £8m by their union for the release of their players to France this year. They can afford to take a season off."

A week ago, it seemed that the French clubs had withdrawn their threat to pull out of Europe - seven are taking part in the season's Heineken Cup - but Blanco was angered by two newspaper reports at the weekend: the intention, strenuously denied, of the RFU to replaces its 12 leading clubs with 10 franchises and the statement of the International Rugby Board chairman, Syd Millar, that he favoured the creation of a new international competition to be played in between World Cups.

"With England intent on franchises and the IRB wanting more international fixtures, the club game will die unless we take a stand," said Blanco. "We had to take action. Europe is the only means we have to protest against an international calendar which does not take club rugby into account. If we do nothing, we will be suffocated. Our league is being devalued commercially and on the playing front. If the clubs are weak, the France team will be. We want the international calendar cut from 11 matches and World Cup campaigns reduced from seven to five weeks."

The Narbonne chief executive, Samuel Gauthier, said the boycott was a bargaining tool. "It gives us a means of negotiation," he explained. "Blanco is looking for a response from unions, the International Rugby Board and ERC. Our league must not lose its importance."

Premier Rugby is holding a board meeting on Monday when it will discuss its reaction. Some chief executives argue that it would be prudent to give the European tournaments a sabbatical next season but the Celts are unlikely to agree.

If the French do not take part, English clubs will lose £75,000 each through reduced television income, while gate receipts and sponsorship will suffer if the likes of Toulouse, Biarritz and Stade Français are replaced by, for example, Viadana, Connacht and Bucharest, leaving a potential deficit for each club of some £200,000.

Heineken, which withdrew its backing when English clubs boycotted Europe in 1998, is monitoring events. "We will wait until something definite happens before deciding our next move, " said its sponsorship manager, Jonathan Lane. Heineken has two years to run on its deal and its concern will be the English clubs committing themselves beyond 2009.

Feud at a glance

Why have the French clubs boycotted Europe? They say it is because England is holding up the signing of a new tournament accord, but the underlying reason is the fixture congestion next season's World Cup in France will cause, for which they have been compensated.

Will the English clubs follow suit? No. They are bound by the long-form agreement with the RFU to play in Europe until the end of 2008-09.

Will Heineken pull out? Unlikely. It will be more concerned about signing a new accord with English teams only committed to Europe for another two years, when its sponsorship runs out.

What happens next? The French could be enticed back but they will need a face-saving concession, such as a reorganisation of league fixtures.