Ali Imron has co-operated with investigators

Reporters spotted him laughing and joking with Brigadier-General Gorries Mere, one of the officers investigating the Bali attacks.

A police spokesman said the excursion was part of an ongoing effort to investigate cases of terrorism.

But the father of a man who died in the 2002 bombings said he was outraged at the excursion.

Ali Imron was sentenced to life in jail last September, for his role in the Bali nightclub blasts.

He is the younger brother of two other key Bali bombers who are now on death row - Amrozi and Mukhlas.

Ali Imron was spared the death penalty after appearing remorseful and repeatedly apologising for his actions.

A police spokesman told the Associated Press news agency that no laws had been broken by the coffee shop trip.

But Yasril Ananta Baharuddin, a legislator from the ruling Golkar party, said he was "shocked" by the "highly inappropriate" outing.

Australian Brian Deegan, whose son Josh died in the Bali blasts, said: "It's extraordinary".

"There are many occasions in Australia where the police might see the need to continue some dialogue with political terrorists... but one wonders why there is this necessity for them to be doing it in a restaurant such as Starbucks as opposed to the jail cafeteria," he told the Associated Press.