SANTIAGO, Chile (UPI) - A huge opposition rally urging a plebiscite vote against military leader Gen. Au-gusto Pinochet erupted Sunday into battles between police and rock-throwing youths. Nine people were wounded, five seriously, and 262 were arrested, police said.The rally, which organizers said was attended by more than 200,000 people and was the biggest in the 15 years of Pinochet's rule, was the first massive show of opposition force since the 72-year-old general was named by the ruling junta as the only candidate in an Oct. 5 plebiscite.

A "Yes" vote in the plebiscite will mean eight more years as president for Pinochet, who came to power in a Sept. 11, 1973, coup. A "No" vote would lead to an open election in 1989.

Sunday's rally, attended by youths and many middle-age people who brought along children, was peaceful until marchers from the gathering reached the central part of the city some three miles away, where the battles began when some 15,000 youths refused to disperse.

Police using mobile water cannons sprayed water at youths and let loose with clouds of tear gas within a block of the presidential palace after the rally.

Crowds of young people threw rocks and clumps of dirt at police, then ran when the water cannons and tear gas trucks approached.

Police said one policeman was wounded along with eight civilians, five of them seriously.

They reported that 262 protesters were arrested on charges ranging from causing property damage, carrying arms and contributing to "general disorder."

The rally, held on the day when Chile in the past traditionally voted in presidential elections, was the first since a state of emergency in place since the coup was lifted. Among other provisions, it had allowed military authorities to deny permission for public meetings and allowed detention without legal process for 20 days.

Pinochet, in an interview Sunday in the capital's leading newspaper, El Mercurio, indicated for the first time he may step down as commander in chief of the armed forces if approved in the plebiscite.