* Juve exec says Super League not a 'menace' to national leagues
* UEFA threats illegal, says Agnelli
* Super League has written to UEFA and FIFA to negotiate
ROME, April 21 (Reuters) - The Super League project is going ahead and has a 100% chance of being a success despite the six English Premier League clubs quitting, Juventus President Andrea Agnelli said in an interview with an Italian daily published on Wednesday.
The interview was carried out before a meeting by the European Super League (ESL) late on Tuesday.
"There is a blood pact among our clubs, we will press ahead," Agnelli told newspaper la Repubblica when asked whether the Super League was sinking after some clubs had decided to leave two days after the breakaway plan was launched.
Having triggered an enormous backlash from players, fans and football authorities, the league was reduced to three teams each from Spain and Italy within 48 hours of its launch on Sunday.
But Agnelli said that the project still had "a 100% chance of being a success".
Serie A champions Juventus are one of the 12 teams who proposed forming the breakaway competition. Agnelli is a key figure in the move and has been named ESL vice-chairman.
The Super League was not a "menace" to national competitions, said Agnelli, and the clubs involved in the breakaway European competition had "full willingness" to continue taking part in them.
European soccer's governing body UEFA has threatened to ban the clubs forming the Super League from domestic and international competition, but Agnelli said that this would not happen.
"It would be a serious abuse. What they are threatening is illegal, and should it happen it would not only be a monopoly but a dictatorship," Agnelli said.
"(World soccer governing body) FIFA and UEFA make revenues with our players but did not help us in moments of crisis. They must choose, either they are regulators or they are commercial promoters," he added.
The Juventus executive said the Super League had written letters to both UEFA and FIFA, hoping to open negotiations with them.
He said that should UEFA make a proposal the Super League will assess it, otherwise "there will be a confrontation on the technical and legal reasons". (Reporting by Giulia Segreti, editing by Lincoln Feast/Peter Rutherford)