Students threw rocks at police who returned fire with tear gas and water cannons during one of several rallies across Indonesia on Wednesday to demand government action to end widespread corruption among politicians, police and other public officials.

More than two dozen rallies _ annual events in this Muslim-dominated nation to mark International Anti-Corruption Day _ were planned for the national capital of Jakarta and several of Indonesia's other larger cities. President Susilo Bambang Yudhoyono is under pressure to act after winning re-election in July on promises of stamping out graft.

Scores of students armed with rocks and wooden planks clashed with anti-riot police and vandalized commercial buildings at a rally in Makassar, the South Sulawesi provincial capital 1,000 miles (1,600 kilometers) northeast of Jakarta.

Police fired tear gas canisters and water cannons to break up the crowd after protesters tried to storm the provincial governor's office. There was no immediate report of injuries or arrests among the 2,000 protesters.

"We want the government not only talking about eliminating corruption," said Amang Wijaya, a 19-year-old student in Makassar. "But we want the government really prosecuting officials who are making the country bankrupt."

In Jakarta, a dozen rallies caused downtown traffic chaos in this city of 13 million.

Thousands marched peacefully on to the presidential palace, some burning pictures of Yudhoyono, Vice President Boediono, who goes by only one name, and Finance Minister Sri Mulyani.

They called on Yudhoyono to address the crowd, but the president had left Jakarta for a meeting in Bali.

Hundreds of anti-riot police were stationed outside his palace.

"Today's rally's aim is not to attack politically any party," protest organizer Usman Hamid said. "We just want to send a message to our fellow countrymen ... that justice cannot be served while corruption is still rampant in our country."

As well as in Jakarta and Makassar, large rallies were also staged in towns and cities across the archipelago in Pamekasan, Bandung, Surabaya, Jayapura, Palu, Jember, Solo, Semarang, Banda Aceh, Malang and Palembang.

Yudhoyono's popularity has already been tested by scandals surrounding Indonesia's anti-graft commission and a 6.76 trillion rupiah (US$715 million) government bailout of a bank. Earlier this week, he told The Jakarta Post that he believed the protests were partly aimed at destabilizing his government.

"My logic says these political movements want to discredit, shake and topple me in the short term," the newspaper quoted him as saying Monday.