Indonesia's top court on Tuesday rejected a request by three death-row Bali bombers to have their executions carried out by a different method than firing squad, saying that the alternatives also were painful.

"The pain suffered by the death-convicted is a legal consequence linked to the execution," Chief Judge Muhammad Mahfud said.

Lawyers for the three death-row Bali bombers had asked the country's Constitutional Court to consider the legality of death by firing squad, arguing it was "unconstitutional" because the men might not die immediately and calling the method a form of "torture."

The lawyers said the condemned militants wanted the death sentences to be conducted by traditional Islamic-style decapitation instead.

But the court on Tuesday rejected the argument, saying all execution methods carried some risk that death would not be immediate.

"There is no way to guarantee there will be no pain. All have a risk of inaccuracy, and will create suffering, but it's not torture," Mahfud said, adding that "the plaintiffs' request is not based on law, and must be rejected."

The three - Imam Samudra, Amrozi and his brother Ali Ghufron alias Mukhlas - received death sentences over their roles in the 2002 Bali bombings, which killed 202 people, mostly foreign visitors. The three have never shown remorse for the bombings of the two nightspots.

The Indonesian Attorney General's office is expected to announce details of the executions on Friday. Prosecutors have said the three should be executed by the end of the year.

Imam Samudra, Mukhlas and Amrozi, known also as the "smiling assassin," were members of Jemaah Islamiyah, the al-Qaeda-linked regional terrorist network responsible for several bombings across Indonesia.

These include simultaneous church bombings on Christmas Eve 2000, bombings on Bali in 2002 and 2005, the bombing of a JW Marriott hotel in Jakarta in 2004 and an attack on the Australian Embassy in 2005.

Indonesian authorities have arrested and jailed hundreds of militants in the past few years, seriously damaging the group, terrorism experts say.