Former Halifax player Gannon has taken out British citizenship

O'Neill, who made only 11 appearances for the Rhinos in an injury-hit season, joins on a one-year deal.

Gannon, 29, a member of the Giants' Challenge Cup final team, has signed a two-year contract.

The club have also released five players, including former Leeds winger Leroy Rivett.

O'Neill, who won the NRL Grand Final with Wests Tigers before joining Leeds a year ago, is looking forward to kick-starting his career.

(Jim Gannon) is a no-nonsense front rower with bags of Super League experience Paul Lakin Hull KR chief executive

"After an injury-wrecked season at Leeds I am really looking forward to showing what a fully fit Mark O'Neill can do," he said.

"I am coming over to an outstanding club that is professionally run. The facilities are great and they are a great bunch of blokes.

"But it is a challenge and we have got a lot of young kids, who are very keen, enthusiastic and full of confidence."

Rovers chief executive Paul Lakin added: "In Mark, we have signed a forward of the highest calibre and one who has played at the highest level all his career.

"His leadership skills and expertise will prove invaluable.

"Jim is exactly the type of prop that Justin Morgan was looking for to complement our current front rowers and also the additional players we have identified.

"He is a no-nonsense front rower with bags of Super League experience."

Rivett, 29, scored four tries in the 1999 Challenge Cup final and was in the Rovers team that beat Widnes in the National League Grand Final.

French centre Damien Couturier and forwards Andy Ellis, Dwayne Barker and Gareth Price have also been released.

Former Leeds forward Jason Netherton has agreed a new one-year deal and winger Jon Steel and former Bradford half-back Matty Brooks are still in negotiations.

But prop James Garmston has been told he can join a National League One club on a season-long loan, and former Huddersfield hooker Phil Joseph has been given permission to speak to other clubs.

Both have a year left on their contracts.