Updated

Three militants awaiting execution for the 2002 Bali bombings plan to challenge the legality of death by firing squad, but it was unclear if the move would lead to a last-minute stay, their lawyer said Tuesday.

Mahendradatta, who goes by a single name, said he would file a petition next week at the Constitutional Court arguing that convicts who go before a firing squad sometimes do not die immediately, causing unnecessary suffering.

"We're seeking an execution without pain," said the lawyer, who in the past has argued that his clients would prefer to be beheaded, which they say is more in line with Islamic teachings.

Ali Ghufron, Imam Samudra and Amrozi Nurhasyim were convicted in 2003 of planning and helping to carry out the Oct. 12 suicide bombings targeting two packed nightclubs on Bali island, killing 202 people, mostly foreign tourists.

The three, who have admitted taking part in the attacks, already have exhausted the appeals process.

Attorney General spokesman Bonaventura Daulat Nainggolan declined to say whether the petition would result in an automatic last-minute stay in their executions, which authorities have said would likely be carried out before September.

Mahendradatta acknowledged the executions could well go ahead even if the case was lodged at the Constitutional Court, but said it would be "murder" if they did.

The Bali attacks were carried out by members and associates of Jemaah Islamiyah, a local network of mostly Afghan trained militants, with al-Qaida providing money and some expertise, police and former militants have said.

Islamic militants have carried out three other major attacks on Western targets in Indonesia since then, the last in 2005, also on Bali, when three suicide bombers killed 21 people in restaurant attacks.