DUBLIN (Reuters) - Ireland's Jonathan Sexton will join French side Racing Metro next season after the Irish Rugby Football Union (IRFU) said on Friday the flyhalf would not be renewing his contract with European champions Leinster.

Sexton, who won three Heineken Cups in four seasons with Leinster and has become one of Ireland's most influential players, has been offered a two-year contract with the Paris-based side, a source close to the deal told Reuters.

Racing declined to confirm the transfer and cannot make any comment before April 21 as under French rules the signing of a player can only be made public when the league's transfer window for the season opens.

The IRFU said it had made the 27-year-old a very strong offer but that ultimately "it would not be in the best interest of Irish rugby to chase the reported financial incentives being offered".

"Naturally, I'm disappointed. The offer he has received is exceptional, even by French standards, but I know that it was still a tough decision for him," Leinster coach Joe Schmidt added in a joint statement.

The big-money move caps a remarkable rise for Sexton who was playing alongside amateur players in Ireland's club league just four years ago, after briefly losing his Leinster squad place.

He led Leinster to their first European success five months later, kicking a spectacular drop goal from halfway in the 2009 win over Leicester, and wrested the Irish flyhalf jersey from Ronan O'Gara during the next couple of years.

The tall number 10, who had not yet been capped by Ireland when the British and Irish Lions last went on tour, will likely be among the starting XV when the Lions take on Australia in three tests this year.

Unlike in New Zealand where players who move abroad become ineligible to represent the national team, Sexton will remain available to play for Ireland, although the demanding French season will mean he misses some national team training camps.

However, the move is a big blow for Leinster who are reliant on the IRFU to keep their main Irish internationals under central contracts.

Leinster, who may also have to replace Brian O'Driscoll if the former Ireland captain decides to retire at the end of the season, last week failed to qualify for the knockout stages of the Heineken Cup for just the second time in nine seasons.

Sexton's signing is a big coup for Racing, who last won the French championship in 1990 and currently lie ninth in the league but have big ambitions under their chairman, property tycoon Jacky Lorenzetti.

(Additional reporting by Gregory Blachier in Paris; Editing by John Mehaffey)

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