Estonia congratulated Monday Ukraine's pro-Western opposition leader Viktor Yushchenko on winning the weekend presidential election, saying it opened new prospects for cooperation with the European Union.

"I congratulate you on the election victory," Foreign Minister Kristiina Ojuland wrote to Yushchenko.

"We regard your victory as a victory of democracy and fair competition, opening for Ukraine new prospects for cooperation with the EU countries, including Estonia," Ojuland wrote according to the foreign ministry.

With nearly all ballots counted from Sunday's re-run election Yushchenko had an unassailable lead of 52 to 44 percent against his rival Prime Minister Viktor Yanukovich.

The pro-Russia Yanukovich has refused to concede defeat and vowed to appeal the results before the supreme court.

Yushchenko campaigned on promises to introduce far-reaching reforms and set Ukraine on a course to join the EU and the NATO military alliance.

Asked whether Ukraine should become a member of the EU in the future, a spokeswoman for the Estonian foreign ministry told AFP: "Ukraine is a very significant partner for the EU, it has a balancing role to play.

The EU must give Ukraine a clear European perspective. But Ukraine must do its own homework regarding the EU first."

Estonia, a former Soviet republic like Ukraine, joined the EU and NATO earlier this year.