In a news conference he appealed to other nuclear-capable countries not to use Wednesday's vote as an excuse to resume or begin testing.

The BBC's Paul Reynolds: 'An angry President Clinton laid into the Republican Senators'.

Despite President Clinton's championing of the treaty, the United States became the first nuclear power to reject the 154-nation agreement on the Comprehensive Test Ban Treaty.

He said the "new isolationism" could be seen not only in the Senate vote, but in "Congress' delinquency" on paying its UN dues and a "woefully inadequate budget for foreign affairs."

"This was partisan politics of the worst kind, because it was so blatant, and because of the risks it poses to the safety of the American people and the world," Mr Clinton said.

On a largely party line vote, the Senate defeated the treaty late Wednesday, 51-48. Only four Republicans voted for the treaty.

"I call on Russia, China, Britain, France and all other countries to continue to refrain from testing," Mr Clinton said.

"When all is said and done I have no doubt that the United States will ratify this treaty."

In the meantime, the US is to continue its moratorium on nuclear tests.

Russia's reaction to the vote was to express reluctance to formally end nuclear testing; but China and India said they would continue moves towards ratification.

President Clinton was the first world leader to sign the treaty in 1996 and has set nuclear non-proliferation as a major foreign policy goal.

His vice-president, Al Gore, is promising to make the arms control vote a key campaign issue in his fight for the presidency in 2000.

'What the people want'

Democrats claimed that polls showed most Americans favoured such a ban - first proposed by President Dwight Eisenhower in 1958 and endorsed, in various forms, by every president since then.

Opponents claimed the compliance with the treaty could not be verified and argued that it would do little to stop terrorist organisations or dictators from developing nuclear weapons.

They also argued the treaty would undermine confidence in the safety and reliability of the US nuclear arsenal.