The October 12, 2002, attacks on nightclubs in Bali's tourist district killed 202 people. The blasts were a watershed for Indonesia, which has the world's largest Muslim population, forcing the secular state to confront the presence of violent Islamists.

Indonesia has been largely successful in containing militancy and there have been no big attacks on Western targets since 2009, when suicide bombers attacked two hotels in the capital, Jakarta, killing nine people and wounding 53.

But the warning over Friday's commemoration, which Australian Prime Minister Julia Gillard and Indonesian President Susilo Bambang Yudhoyono are due to attend, is a reminder of the lingering danger.

"From the information that we have gathered, there are indications of movements aimed at VIPs who will attend the event," Deputy Chief of Bali Police Ketut Untung Yoga Ana said on Wednesday. "Therefore, the police and army forces, including the community, have made sure their readiness."

Commemorations will be held in various parts of Bali including the Kuta Beach area where the nightclubs, packed with mostly young foreign tourists, were attacked.

Among the dead were 88 Australians. About 4,000 foreign visitors are due to attend the ceremonies.

Yoga Ana said police had brought in reinforcements from Jakarta and the military was also helping with security.

" There are 1,003 police officers in Bali and 118 personnel reinforcements from headquarters," he said.

"This excludes security officers for VIPs from the TNI which will be as many as 1,000 personnel," he added, referring to the armed forces.

After the bombings, security forces detained nearly 600 militants, most of whom have been jailed.

Three main perpetrators of the bombings, members of a Southeast Asian militant group allied with al Qaeda, were convicted and executed by firing squad in 2008.

In March, police shot dead five suspected militants planning attacks on Bali, including an assault on a night club popular with foreign tourists, the national counter-terrorism agency and police said. (Reporting by Heru Asprihanto; Writing by Michael Taylor; Editing by Robert Birsel)

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