Reports involving the "certain movement" of terrorists have been received, said Bali Police Brig. Gen. I Ketut Untung Yoga Ana. He said that security had been tightened at all entry points to the resort island prior to the event, and that snipers would be placed around memorial sites.
"We have prepared a maximum security arrangement, even for the post-commemoration," he said. He declined to provide any specific details about the threat.
However, an intelligence official said information about a potential threat first surfaced prior to Oct. 1, the anniversary of a second Bali bombing in 2005 that killed 20 people at restaurants. The official spoke on condition of anonymity because he was not authorized to speak to the media.
Australian Prime Minister Julia Gillard is scheduled to attend Friday's event remembering the Oct. 12, 2002, attacks that blasted two Bali nightclubs. The bombs killed 202 people, including 88 Australians and seven Americans. The attack was carried out by Jemaah Islamiyah, an al-Qaida-linked group.
Gillard said Wednesday that she was still planning to attend the service.
"Families will be travelling there, it will be a day in which we will pay our respects, and remember
A ceremony will be held Friday at a park in Jimbaran followed by a ground-zero memorial in Kuta.
Former Australian Prime Minister John Howard, U.S. Ambassador to Indonesia Scot Marciel and diplomats from elsewhere are expected to attend. Hundreds of survivors of the bombings and victims' family members will also gather.
"It is better not to underestimate. ... It is better to carry out an excessive security arrangement rather than being defeated," said Bali police Chief Maj. Gen. Budi Gunawan. "At stake is the image of Indonesia's police."
Meanwhile, Bali Governor Made Mangku Pastika, the former police chief who led the investigations following the 2002 bombings, apologized to the victims' families Wednesday and called for them to try to forgive.
"Indeed, it is not easy to forget such a deadly incident, but the time has come for us to have to forgive the terror actions," Pastika told a news conference. "It's the commemoration to forgive and to start a new life."
After a massive crackdown on Muslim extremists, terrorist attacks aimed at foreigners in Indonesia have been largely replaced in recent years by smaller, less deadly strikes targeting the government.