United Nations Secretary-General Kofi Annan on Wednesday congratulated US President George W. Bush on his re-election and hoped to maintain "positive and productive" relations between the world body and the US government, a UN spokesman said.

Annan also praised the American people for their active participation in Tuesday's election and Bush's challenger, Senator John Kerry, for "his prompt and statesmanlike decision to accept the outcome," Fred Eckhard said at the daily noon briefing.

The American people gave an "impressive" demonstration of democracy by "turning out in record numbers to participate in yesterday's election," the spokesman said.

US media reports said about 120 million Americans were expected to have cast ballots, or just under 60 percent of eligible voters -- the country's highest percentage turnout since 1968.

Kerry's campaign officials said the Democratic candidate phoned Bush on Wednesday morning to concede defeat.

Eckhard said the secretary-general "is committed to continuing to work with President Bush on his administration on the whole range of issues facing the United Nations and the world."

The UN-US relations were "positive and productive" in the past four years, despite disagreements on such issues as the US-led invasion of Iraq, he said, adding that Annan expected another four years of such relations.