Fitzpatrick came on as a replacement for Ireland against England

The Ulster Branch (IRFU) announced on Thursday evening that Fitzpatrick would not be renewing his contract.

An Ulster statement did not make clear where Fitzpatrick was moving to but BBC Sport has learned that he will be signing for Jeremy Davidson's former club.

It is understood that he will get an increased financial package at the French club.

The 29-year-old has a young family and felt it impossible to turn down such a lucrative offer at this stage of his career.

Fitzpatrick fought back into the Irish squad this year after producing a fine season for Ulster.

He came on as a replacement in Ireland's final Six Nations games against Wales and England which brought his total of international caps to 23.

The Essex-born prop signed for Ulster from London Irish in 1998 and helped the Irish province claim the European Cup a year later.

He was also a member of Dungannon's 2000 All-Ireland League title winners.

Also in 1999, he was an ever-present for Ireland in the World Cup, but then lost his international contract.

Justin has contributed a huge amount to Ulster Rugby Ulster chief Michael Reid

However, with the arrival of Springbok Robbie Kempson and Kiwi Matt Sexton, Fitzpatrick's game rose in stature and he fought his way back into the international squad.

Fitzpatrick's basic salary is not that much improved from his provincial contract.

However, with tax exemptions and the provision of a house and car, the affable prop will be much better off.

Ulster chief executive Michael Reid said that the branch was sorry to lose Fitzpatrick but that it "understood the decision".

"Justin has contributed a huge amount to Ulster rugby, both on and off the field and I wish him well," said the Ulster official.

Fitzpatrick's departure means that Ulster will have major vacancies to fill in the front-row at the start of the season.

Along with Fitzpatrick, Kempson will miss the early stages of the Celtic League campaign because he will be in action for South Africa in the World Cup.