Anti-Lisbon Sinn Fein lose key EU seat in Ireland

DUBLIN (Reuters) - Ireland's nationalist Sinn Fein party, a major opponent of the European Union's reform treaty, lost its European Parliament seat for the Dublin constituency on Monday.

In a marathon count in the Irish capital, incumbent MEP Mary-Lou McDonald failed to reach the necessary quota required to keep her party's only EU seat from the Irish Republic.

It leaves Eoin Ryan of Ireland's ruling Fianna Fail Party fighting to hold on to the final seat against Joe Higgins of the Socialist Party.

Bairbre de Bruin is expected to hold on to her EU assembly seat for Sinn Fein in Northern Ireland, where counting begins later on Monday.

Sinn Fein is the only major elected party in Ireland to oppose the EU's Lisbon reform treaty which was rejected by Irish voters last year.

Ireland is expected to hold a second vote on the treaty -- aimed at streamlining decision-making in the bloc -- later this year.

Earlier on Monday, Gay Mitchell of Fine Gael -- Ireland's main opposition party -- and Pronssias Proinsias de Rossa retained their European seats in the three-seat Dublin constituency.

(Reporting by Darren Ennis; editing by Michael Roddy)