Death-row bombers Amrozi, his brother Mukhlas and Imam Samudra may be put before a firing squad any day now, with all legal processes in Indonesia now exhausted.

Indonesia's Supreme Court has dismissed the bombers' final legal challenge, and Australians who lost family members and friends have been told the executions are ''imminent''.

Indonesian authorities must now inform the Islamic militants of the ruling, and will offer them one last opportunity to seek clemency from President Susilo Bambang Yudhoyono.

But the bombers have repeatedly said they will not seek clemency, and want to die as martyrs.

The men's families have been preparing for the executions for the past month, buying the white clothes the bombers want to wear when they are put before a firing squad.

After so many delays in the case, some Australian families are elated that the men are living out their last days.

Victorian man David ''Spike'' Stewart, whose son Anthony was killed, said the Australian Federal Police had informed him the executions were imminent.

He said he would celebrate the executions with a beer.

''Once it happens, we'll probably be the first ones to know, the AFP will ring us straight up and say, 'They're gone' and I'll be a very happy man,'' he said.

''Believe me, if they gave me the rifle I'd do it today, no hesitation. I'd want him [the so-called smiling assassin, Amrozi] to be looking at me smiling while I pulled the trigger.''

But other families say the day the bombers are executed will be a dark one.

Former Adelaide magistrate Brian Deegan, whose son Joshua was killed in the blast, said the death penalty was deplorable and barbaric even in this case.

He said, ''Well before Joshua died I formed the view that the death penalty was deplorable on any level, for any reason, and is in itself a barbaric act that diminishes society and has no particular positives.''

Indonesia's Supreme Court spokesman Nurhadi, who goes by one name, said the bombers had now exhausted all legal options.

''They can be executed, as long as they don't submit a clemency request,'' he said.

''The legal court processes have been finished: it's already final.''

He said the Supreme Court had sent a letter to Bali's Denpasar District Court on Sunday saying the men were entitled to one judicial review only, which they had been afforded and lost.

Requests for additional reviews had no basis in law.

''Indonesian law regulates that a judicial review can only be submitted once. If it is submitted a second or third time, that means it is in violation of laws,'' he said.

A spokesman for the Indonesian Attorney-General's Office said the Supreme Court ruling would now be conveyed to the bombers at their jail on Nusakambangan island in central Java.

They would also be notified of their opportunity to seek presidential clemency.

But the men's families are clearly expecting the executions will proceed.

The brother of Amrozi and Mukhlas, Muhammad Chozin, said last month his family had bought plain white clothes for the men to wear when they were put to death.

The bombers have told their families in their wills that they want Islamic funerals, with a plain white cloth to cover their dead bodies.

Indonesia does not make public the timing and exact location of executions, but a deputy attorney-general said last month they would take place in central Java.

Indonesia appears to be ramping up its use of the death penalty despite a global push to eliminate state-sanctioned executions.

A mother and son are due to face the firing squad, possibly today, in eastern Java over the murder of a family of five.

If the two death sentences are carried out, Indonesia will have executed five prisoners in less than a month.

Late last month, two Nigerian men were executed for heroin smuggling the first drug-related executions in four years.