Survivors, family and friends of victims of the 2002 terrorist bombings on the Indonesian resort island of Bali marked the 6th anniversary of the attacks on Sunday with low-key ceremonies.

The widows of several Balinese men, along with family members of more than a dozen other Indonesian victims, laid flowers and prayed at a memorial monument in the Kuta Beach district, where twin bombs at two nightclubs killed 202 people and injured hundreds more on October 12, 2002.

Most of the victims were foreign tourists from more than a dozen Western and Asian nations, targeted by the regional terrorist group Jemaah Islamiyah (JI), a South-East Asian offshoot of al-Qaeda blamed for several terrorist attacks across in Indonesia in recent years.

At the Australian consulate on Bali, a memorial service was attended by the ambassador to Indonesia and the island's governor, as well as dozens of survivors, friends and family of the 88 Australians who died in the attacks.

"The 12 October 2002 tragedy shocked Australia. For those who lost loved ones, life will never be the same," Prime Minister Kevin Rudd said in a statement read by the ambassador.

In 2003, an Indonesian court sentenced alleged JI members Imam Samudra, Ali Ghufron, and his younger brother Amrozi to death for the attacks. The plot included a suicide bomber at a small pub on Kuta Beach's Legian Street, followed seconds later by a huge car bomb across the road outside a nightclub packed with Western tourists.

Authorities promised recently that Samudra, Ghufron and Anrozi, known also as the "smiling assassin," would be executed by the end of this year. Prosecutors had earlier put plans on hold to execute the bombers before the Muslim holy month of Ramadan on September, citing bureaucratic delays.

Indonesian counter-terrorism police have arrested more than 400 JI members in the past five years and sent dozens to prison under a tough anti-terrorism law.

The group is also accused of bombing dozens of churches on Christmas Eve 2000; triple-suicide bombings on Bali in 2005; a truck bombing of the JW Marriott Hotel in Jakarta in 2004; and a truck bombing outside the Australian embassy in Jakarta in 2003.