Some 1,000 opponents of the U.S. anti-missile radar base rallied at a demonstration in the center of Prague on Saturday, police said.

The demonstrators carried posters, expressed their opposition to the U.S. project by whistling, chanting slogans and blowing sirens, and also distributed leaflets.

Lower house deputy chairman Lubomir Zaoralek and former Czech foreign minister Jan Kavan took part in the demonstration.

Members of the junior ruling Green Party (SZ) from all over the Czech Republic turned up at Prague's Wenceslas square to voice protest against the project on which the Czech government has been officially negotiating with the United States since early May.

Matej Stropnicky, a member of the SZ national council, said the SZ rejects the U.S. doctrine of preventive war and the anti-missile defense.

Nevertheless, the SZ is waiting as some SZ leaders believe that the United States will drop the base construction plan, Stropnicky said.

Speakers at the demonstration called for the Czechs not to allow themselves to be manipulated into the American game aimed at enhancing the U.S. armament companies' profit.

The United States unveiled its plan in January to place a radar system in the Czech Republic and 10 interceptor missiles in Poland,as components of the anti-missile shield.

The ruling Civic Democrats (ODS), the Christian Democrats (KDU-CSL) and a large part of the Greens (SZ) said they would welcome the plan if the missile defense shield were integrated with NATO, while the opposition party Social Democrats (CSSD) and the Communists (KSCM) are against the project.

According to public opinion polls, about three-fifths of Czechsare opposed to the project, and three-fourths want the issue to be settled through a referendum.

U.S. President George. W. Bush is expected to discuss the radar project with top Czech leaders during his visit to Prague in early June.

Czech activists want to stage demonstrations during Bush's stay in the Czech Republic.