Belgrade - The United States and the European Union hailed Monday the outcome of snap polls in Serbia, saying voters sent a "clear signal" in favour of the troubled country's further progress towards European Union membership.

The European Commission, the EU's executive, "welcomes the success of the reformist forces that share European values. This should enable swiftly forming a new government," EU Enlargement Commissioner Olli Rehn said.

"I hope that a new government can be formed rapidly, which would be strongly committed to reforms and to meeting the necessary conditions for further progress towards Europe," EU foreign-policy chief Javier Solana said, promising such government "all support."

The European Union had already on Sunday welcomed what it said was a "clear victory" of pro-European forces grouped behind President Boris Tadic.

Tadic's camp won 39 per cent of votes, but is still far from a majority and faces hard talks in a bid to convert the poll result into power and keep Serbia on a Western course.

The anti-European bloc also has a shot at a majority coalition and has already launched talks aimed at securing it.

Tadic's nationalist rivals want to steer the country away from EU membership in protest at Western support of Kosovo's secession.

Washington joined in the congratulations, with the US embassy in Belgrade saying "the Serbian electorate clearly demonstrated that its heart is in Europe."

German Foreign Minister Frank-Walter Steinmeier congratulated Tadic on an "impressive victory ... providing the foundation for the upcoming government-building."

The French Foreign Ministry said the election outcome was a "distinctive vote for Europe" and promised to support Serbia's EU membership bid.

Referring to pre-election surveys which had tipped a nationalist victory, Swedish Foreign Minister Carl Bildt - who served as a mediator and an international representative in former Yugoslavia - welcomed the outcome as "much better than expected."

The Organization for Security and Cooperation in Europe (OSCE), which monitored Serbian elections, praised the "overall professional manner" and "most impressive fashion" in which it was organized.

"The campaign environment was pluralistic and open, with extensive media coverage, but also marred by incidents of threats against leading politicians' lives," the OSCE monitoring mission said in a statement a day after the poll.

Some local media reported last week that Tadic received death threats in a letter. Tadic's office declined to comment.

The Serbian poll was closely watched in the former Yugoslavia, which disintegrated in a series of wars with Belgrade - in Slovenia, Croatia, Bosnia and Kosovo - during the
1990s.

In Kosovo, where the Albanian majority declared independence from Serbia only three months ago, officials said a "win by (Tadic's) Democrats" in Serbia could help the entire region integrate with the EU.

"When neighbouring governments ... are democratic and pro- European, it will certainly lead to better cooperation in the region," Kosovo's deputy premier Hajredin Kuchi told Britain's BBC.

Kuchi said Pristina was "interested in good neighbourly relations" with Serbia, but Tadic's first words after he declared victory were that he would never recognize Kosovo's independence.

In Montenegro, which peacefully divorced Serbia in 2006, both the authorities and opposition welcomed the election outcome as a sign that "Serbs opted for economic growth and the EU."

"The election outcome in Serbia is a good signal to the entire region," said Predrag Sekulic, a top official from the ruling Democratic Party of Socialists.

In Macedonia, where fragile stability relies heavily on stability in Serbia, the outgoing cabinet welcomed the Serbian poll and promised to work with Belgrade.

"The elections in Serbia demonstrated that the Balkans are on a stable march to Euro-Atlantic integrations," the caretaker cabinet spokesman Ivica Bocevski said.

Macedonia holds early parliamentary polls on June 1 amid persistent ethnic tensions that brought majority Slavs and minority Albanians to the verge of civil war in 2001. (dpa)