By Ian Ransom

MELBOURNE (Reuters) - European nations have long cleaned up at Olympic handball but at the Rio de Janeiro Games, their dominance may be ended by their home-grown players competing for Qatar.

Since the 2012 London Olympics, the oil-rich Gulf nation has assembled a formidable roster of naturalized Europeans who helped sweep the last two men's Asian championships and took a stunning silver at last year's world championship on home soil.

European nations have grumbled that Qatar has become a 'world all-stars' team rather than a true national outfit but the Qataris retort that they are just playing by the rules.

The International Handball Federation allows players to switch allegiance if they have not competed for their home nations for three years and handball-mad Europe offers a wellspring of surplus talent.

A Qatari triumph at Rio could prove controversial, given 24 years and five Olympics have passed since a team outside Europe has won gold in the sport in either the men's or women's events.

Olympic champions France, who became the first men's team to win back-to-back golds at London, defied Qatar in the final at the world championships and will hope to repel them again at Rio in their bid for a hat-trick of titles.

France have not had it all their way since, however, finishing a disappointing fifth at the European championships in January where Germany defeated Spain in the final.

Norway will also aim for a hat-trick of Olympic titles in the women's event to match Denmark's triple from 1996-2004.

Apart from Brazil, who earned an automatic berth as hosts, only Argentina, South Korea and Angola stand in the way of European domination in the women's event.

The tournament will be held in the main Olympic Park's aptly-named Future Arena, a visually striking building that was completed well ahead of schedule.

The Arena will be dismantled after the Games and its materials recycled for the construction of a number of schools as part of organizers' legacy pledge.

(Editing by Pritha Sarkar)