Marshall joined Leeds at the start of last season

Marshall has a year to run on his two-year deal but asked to be released after meeting Leeds chief executive Gary Hetherington.

"We're disappointed at the prospect of losing him. We've reluctantly agreed to make him available," said Hetherington.

Marshall, 32, said: "I am grateful to the club for allowing me to explore other opportunities."

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Marshall joined Leeds at the start of last season but his class and experience could not help the club avoid the drop.

"I have enjoyed my experience at Leeds and in the Premiership and I am desperately sorry we find ourselves in this position," he said.

Earlier this month he suggested he would stay with the club but Marshall, who won 81 caps for New Zealand, now says he wants to finish his career playing top-level rugby.

He has been linked with a move to French club Bourgoin and newly-promoted Harlequins.

Earlier on Wednesday, Canterbury Crusaders coach Robbie Deans said Marshall would be sure of a warm welcome if he decided to play out the rest of his career back in New Zealand.

Justin has been a key player for us this season and we hope he will remain here for the challenge that faces us next season Leeds boss Phil Davies

"He's a class act isn't he? I would think New Zealand rugby would be delighted to have him back on the roster," Deans told The Press newspaper.

Leeds have not totally given up hope that Marshall will stay to try to help them make it back to the Premiership.

Director of rugby Phil Davies said: "Justin has been a key player for us this season and we hope he will remain here for the challenge that faces us next season.