Costello has accumulated 39 Test caps but has not started an international since Ireland crashed out of the 2003 World Cup with a comprehensive 43-21 quarter-final defeat by France.

He was a used substitute during last seasons RBS 6 Nations, when Ireland won the Triple Crown, but a broken rib prevented him playing any part in the November internationals.

Eric Miller, Johnny OConnor and Denis Leamy have all leaped ahead of him in the back row pecking order since, freezing Costello out of head coach Eddie OSullivans Test plans.

Costello explained: Ive been thinking about when to retire for the last six months.

Ive been involved in competitive sport for the past 20 years and decided I wanted to leave at the top without any bad memories.

There are lot of things I want to do and places I want to see without having a rugby bag over my shoulder.

I will miss Leinster but its better that we miss each other than hanging around and being forced to leave.

Its heartbreaking but Im proud of making this decision because it means Im embracing my retirement, not running away from it like so many professional sportsmen tend to do.

Costello represented Ireland at the 1992 Barcelona Olympics and OSullivan paid tribute to a gifted athlete who has been involved in competitive sport for more than 20 years.

The coach said: Victor Costello has enjoyed an incredible sporting career of which rugby has played a huge part.

He has been one of the most talented athletes in the game and played a big part in the recent success of the national team, none more so than in the 2003 World Cup.

I wish him every success in his future career plans.

Ireland face Wales in a potential RBS 6 Nations title decider at the Millennium Stadium on Saturday and Costello is backing OSullivans men to gatecrash their Celtic rivals Grand Slam party.

Ireland were very disappointed after losing to France and I think this will forge them together in what will be a high pressure situation, he said.

They have more experience in playing these big games than the Welsh and this will work in their favour. It will be a very tough match but Ireland deserve to win something.