CILACAP, Indonesia (AFP) - A Frenchman on death row in Indonesia was Tuesday transferred under heavy police guard from a prison island, the day before he starts a last-ditch court bid to avoid the firing squad.

Serge Atlaoui has been detained on the island of Nusakambangan in Central Java, known as Indonesia's "Alcatraz", since he was sentenced to death in 2007 on drugs charges.

He is among a group of drug convicts, including nationals from Australia, Brazil, the Philippines, Ghana and Nigeria, who face imminent execution after recently losing their appeals for presidential clemency.

Sabine Atlaoui (centre), wife of French death row prisoner Serge Atlaoui, and other family members disembark from a boat after visiting Nusakambangan prison island located off central Java island on Tuesday. The families of Brazilian and French drug smugglers facing imminent execution in Indonesia visited them on the prison island where they will be put to death by firing squad together with drug convicts from Australia, Ghana, Nigeria and the Philippines. -- PHOTO: AFP

Atlaoui was released on Tuesday evening from one of Nusakambangan's maximum security prisons and taken by ferry to Cilacap, the Javanese port town that is the gateway to the island, according to a reporter at the scene.

He was transferred in handcuffs to a waiting vehicle, where heavily armed police escorted him in a convoy from the port.

A French embassy official confirmed that Atlaoui, 51, was being transferred ahead of his case.

He will travel overland to a court more than 400 kilometres away in Tangerang, an industrial city just west of the capital Jakarta.

On Wednesday, a court in Tangerang will hold an initial hearing into his request for a judicial review of his sentence.

Atlaoui had his appeal for clemency rejected in January by Indonesian President Joko Widodo, a vocal supporter of capital punishment for drug offenders. A request for presidential clemency is typically the final chance to avoid the firing squad.

French death row prisoner Serge Atlaoui, handcuffed in a minivan and guarded by armed police, leaves Wijayapura port in Cilacap from Pasir Putih prison in Nusakambangan prison island located off central Java island on Tuesday. -- PHOTO: AFP

The Frenchman had never lodged a judicial review of his sentence until this year, when the sudden execution in January of six prisoners - including five foreigners - prompted his family to begin urgent legal action.

The father-of-four was arrested near Jakarta in 2005 in a secret laboratory producing ecstasy.

Imprisoned in Indonesia for 10 years, he has always denied the charges, saying he was installing industrial machinery in what he thought was an acrylics factory.

His wife Sabine said in an interview last week she hoped that, through the court case, "the truth can be revealed".

Indonesia's attorney-general has stressed the failed attempts at presidential pardons were the last chance to avoid the firing squad, although he has recently suggested he may wait for legal challenges to conclude before the executions.

The two Australians, Andrew Chan and Myuran Sukumaran, were transferred last week from jail on Bali to Nusakambangan, signalling a date for the executions of the drug convicts could be near.