By Kevin Smith

DUBLIN (Reuters) - Ireland's biggest bookmaker said Thursday it would pay out more than 1 million euros ($1.35 million) on bets that Barack Obama will be the next U.S. president, three weeks before the election.

Dublin-based bookmaker Paddy Power said it made the "unprecedented decision" to pay on bets taken so far, following Wednesday's final campaign debate between Obama and his Republican rival John McCain, which polls judged the Democrat to have won.

"We declare this race well and truly over and congratulate all those who backed Obama," Power said in a statement.

"Although he seemed a little out of sorts in last night's final debate we believe he has done more than enough to get him across the line on November 4."

The bookmaker said the overall betting trend had shown "one-way traffic" for the Illinois senator since the start of the summer, with odds shortening to 1-9, meaning a bet of 9 euros is required to make 1 euro profit.

The odds on McCain winning are 5-1.

Power said it had taken more than 10,000 bets on the 2008 U.S. presidential election, the majority in support of Obama.

In June a wager of 100,000 euros was placed on Obama to win at odds of 1-2, it added.

However, the bookmaker does not always get it right.

In June it paid out more than 80,000 euros in bets that Irish voters would back the European Union's Lisbon treaty in a referendum shortly before the electorate returned a resounding "no."

(Editing by Opheera McDoom)