BELGRADE, Yugoslavia (AP) _ Thousands of students today defied a new police ban on opposition protests amid threats of a crackdown on the most serious challenge to the nine-year rule of Serbian President Slobodan Milosevic.

The first death in the current turmoil _ a 39-year-old man injured after Milosevic supporters beat demonstrators in Belgrade on Tuesday _ was reported today by the opposition and independent media.

In sub-freezing temperatures and snow, about 5,000 students brushed aside a warning from a police officer not to start their march today. The officer, who declined to give his name, said he had orders to break up the protest.

A police warning read on state television late Wednesday announced the ban on demonstrations across Serbia and promised intervention if protesters clogged traffic, as they have nightly for more than a month.

``Police will no longer tolerate the blocking of traffic and therefore it warns organizers of demonstrations ... police will intervene in accordance with the law to protect the rights of citizens,'' the police statement read.

But opposition leaders said they would not be cowed.

``I'm calling on our supporters to ignore the ban,'' said Vuk Draskovic, a leader of the opposition coalition Zajedno, or Together. ``If we show we are afraid now, tomorrow they may forbid us to drink water or breathe air.''

Some students today carried long strings of garlic they said were their defense against ``Communist vampires.'' Balkan superstition has it that garlic wards off evil spirits.

``We will march ... until they fulfill our demands,'' said student leader Cedomir Jovanovic.

Demonstrators have clogged streets in the capital, Belgrade, since courts loyal to Milosevic annulled Nov. 17 municipal elections the opposition had won. Smaller demonstrations have been taking place in other towns across Serbia.

The protests were peaceful until Tuesday, when clashes between Milosevic supporters and opposition members injured 58 people. Opposition supporters accused Milosevic of provoking the violence to give him an excuse to crack down on the protests.

Hundreds of riot police bused into the capital ahead of Tuesday's clashes are still in Belgrade.

The official Tanjug news agency reported that opposition supporters stoned and smashed glass doors of the Socialist Party office in Uzice, 120 miles south of Belgrade, on Wednesday. An attack also was reported Wednesday on Socialist offices in Nis, Serbia's second-largest city.

Neither of the reports could be confirmed independently. Throughout the crisis, state-run news media have sought to portray opposition members as rowdies and hooligans.

Despite Wednesday's stern police warning, federal police minister Vukasin Jokanovic told reporters in the Serbian parliament today that police would not intervene ``if demonstrators do not jeopardize the traffic.'' The statement seemed designed to prevent a further erosion of support for Milosevic, who faces his most serious challenge since taking power in 1987.

Student radio Index reported today that Predrag Starcevic is the first casualty of the uprising against Milosevic. Rade Vasilic, a doctor at Belgrade's Emergency Hospital, told Index that Starcevic died Tuesday night.

Opposition leader Vesna Pesic said Starcevic was beaten up near one of the Sava river bridges that link old and new Belgrade. The protesting students held a minute of silence for him.