The police and the demonstration organizers also disagreed yesterday about arrangements.

The demonstration organizers had instructed the participants not to talk to reporters or other strangers.

The demonstration organizers said it was the first of what they hoped would be 20 to 25 protests across Serbia in the five weeks.

Although the organizers of the demonstration have now been freed, thanks to international pressure, the trial against these 31 politicians is continuing.

Rocard decided to send a letter to the organizers of the demonstration, warning them.

Two weeks ago, 10,000 members of some 30 unions held simultaneous demonstrations in 10 cities across the country, according to the demonstration organizers.

Several local residents, however, accused organizers of the demonstration with provoking a confrontation.

Mr. Stanley, who met earlier with demonstration organizers, said that he was there only to observe.

State and local health departments and demonstration organizers are also working to identify any other reports of possible illness among demonstrators.

"People understand there's a moment here to try to stop this war," said Leslie Cagan, an organizer of the demonstration.