Hundreds of rock-throwing demonstrators tried to storm the closed Union Carbide pesticide plant Saturday on the fourth anniversary of the gas leak that killed more than 3,300 people, but police blocked the charge.

Police said they arrested at least 200 of the protesters. Organizers of the demonstration said about 500 were arrested.Most in the crowd were residents of shantytowns across the road from the plant. Many said they still suffered from the effects of the toxic methyl isocyanate that leaked out of a storage tank and turned into a killer white cloud at about 1 a.m. on Dec. 3, 1984.

The crowd shouted "We want justice" and "Hang Warren Anderson," the Union Carbide president who resigned after the gas leak.

A few demonstrators suffered minor injuries as they scuffled with police wielding steel-tipped bamboo canes. There were no signs of injuries to the police.

Reporters estimated the size of the crowd at 1,000 and the number of uniformed police at 500. Dozens of plain-clothes policemen also were seen moving among the demonstrators.

Five activists from the Communist Party of India, chief organizer of the demonstration, scaled the 8-foot walls surrounding the pesticide plant, which closed after the gas leak and never re-opened.

Plainclothes police behind the wall grabbed four of the men, but the fifth ran to a watchtower and hoisted the red flag of the Communist Party. Both the man and the banner were quickly pulled down.

Police sources who spoke on condition of anonymity said the demonstrators would be released soon without charge. Indian law permits police to hold detainees up to 90 days without charge. Demonstrators usually are held for a few hours or overnight before being freed.

The government of India filed a $3 billion damage suit against the Danbury, Conn.-based company in 1986, but the case is still tied up in Indian courts. Last year, on the third anniversary of the gas leak, the government filed murder charges against Anderson and other Union Carbide officials in India and abroad.

None of the officials has responded to the summonses, and government prosecutors have said they will try to extradite Anderson.

India has accused Union Carbide, whose Indian subsidiary operated the plant, of negligence resulting in the gas leak.

The company says the leak was the result of sabotage by a disgruntled employee.

At least two dozen effigies representing Anderson and Union Carbide were set ablaze near the derelict plant Friday and Saturday.

According to the Madhya Pradesh government, 3,329 people have died from the gas and 20,000 survivors still suffer from its effects.

Gas Relief Commissioner S. Sathyam, a state official whose department records gas deaths and administers relief, said the victims are still dying at a rate of about one a day.