Irish horse trainer Aidan O'Brien has been left in the lurch after his long-term stable jockey Pat Smullen has refused an invitation to replace new and very successful jockey Johnny Murtagh.

Murtagh and O'Brien parted ways earlier this week and it was believed that Smullen would replace Murtagh in the O'Brien camp.

However Smullen said on Tuesday he was perfectly content with his new stable and would pass on the offer to replace Murtagh.

"I've got a very good job and I ride for some very good owners so I'm happy where I am," said Smullen, who has ridden Group One winners in Ireland, France, England and the United States.

"I'm staying with Dermot and very happy to do so. He's a world class trainer and he's got some great owners. I'm very happy in the position I am at the moment."

Murtagh, who has had three tremendous seasons with the world-renowned trainer, announced on Monday he was terminating his partnership with O'Brien.

Murtagh, one of the world's top jockeys, won many of the big races around the world.

His haul includes in Ireland; three 2000 Guineas, one 1000 Guineas, four Irish Derbys, five Irish Oaks, two Tattersalls Gold Cups and an Irish Champion Stakes.

In England his wins include; two 2000 Guineas, three Epsom Derbys, the Eclipse Stakes, three King George VI and Queen Elizabeth Stakes, three Sussex Stakes, three Yorkshire Oaks, the International Stakes, a QEII Stakes and a Champion Stakes, and internationally wins in the Prix de l'Arc de Triomphe, Breeders' Cup Turf, Breeders' Cup Mile, Breeders' Cup Marathon and Hong Kong Vase.

Murtagh, 40, issued a statement on Monday ending his association with O'Brien and other trainers associated with Coolmore Stud operation.

The statement said, "Johnny has spoken to Mr John Magnier, Mr Derrick Smith, Mr Michael Tabor and Mr Aidan O'Brien and informed them that he will not be renewing his contract to ride as stable jockey to Coolmore and Ballydoyle next season, 2011.

"He would like to take this opportunity to thank Mr Magnier, Mr Smith, Mr Tabor and Mr O'Brien for the wonderful and successful three years that they had together and wish all of them and their families every success in the future.

"He would also like to thank Mr David Wachman, Mr Charles O'Brien and Mr Tommy Stack, who also trained Coolmore horses, and again wish them every success next season."

Johnny Murtagh and Aidan O'Brien photography at Royal Ascot