Alleged Bali bomber to face six charges

The man believed to have built the devices used in the first Bali bombings which killed 202 people, including 88 Australians, will be charged with mass murder for his alleged role in the 2002 attacks.

Prosecutors on Monday delivered a 50-page indictment to the West Jakarta District Court where Umar Patek is expected to face trial later this month on six charges related to his suspected involvement in terrorist activities over more than a decade.

Patek, who has allegedly already admitted to a role in the Bali bombings, won't be charged with terrorism offences over the 2002 attacks because Indonesia's tough anti-terrorism laws, introduced in 2003, cannot be applied retrospectively.

However, he will face a charge of premeditated mass murder in relation to the bombing of two nightclubs in the popular holiday area of Kuta 10 years ago, as well as a series of bombings of churches in Indonesia in 2000.

If found guilty of the murder charges he could be sentenced to death.

A copy of the indictment, seen by AAP, also lists charges of conspiracy to commit terrorism, harbouring information on terrorism, possession of explosives and firearms, as well as two counts of document fraud.

Indonesian authorities, including a special counter-terrorism unit with the Attorney-General's Department, have been working on building a watertight case against Patek since his extradition from Pakistan in August last year.

Bambang Suharyadi, one of a team of 15 prosecutors who will be involved in the trial, told AAP on Monday that the indictment covered Patek's alleged involvement in terrorist activities "from the Christmas bombings up to his arrest in Pakistan".

The 43-year-old spent almost 10 years at the top of Southeast Asia's most-wanted list before his capture in January 2011 in Abbottabad, the same Pakistani town where US forces killed al-Qaeda leader Osama bin Laden last May.

Prosecutors will present evidence from up to 80 witnesses during the trial, including testimony from Australian and American survivors who lived through the horror of the Bali attacks.

They will also rely on evidence already provided by Patek, who in October last year retraced his steps in the final hours before bombs were detonated at the Sari Club and Paddy's Bar.

The evidence also includes video of Patek showing police where he finished assembling the bombs.

Patek is the last of the key members of Jemaah Islamiyah (JI) - the group behind the Bali bombings - to face justice over what remains Indonesia's most deadly terrorist attack.

His trial comes after the conviction last year of high-profile JI co-founder and the spiritual leader of the jihadist movement in Indonesia, Abu Bakar Bashir, following the discovery of a secret paramilitary training camp in Aceh.

The bespectacled cleric served almost 26 months behind bars for conspiracy over the 2002 Bali bombings but that conviction was later overturned.

Patek's trial will be conducted amid heavy security, with authorities concerned about the possibility of reprisal attacks from his old network, which they believe may still be active in Indonesia.

It is expected to run until late May or early June.