ROUEN, France (AFP) – The tattooed, shrunken head of a Maori warrior starts a long voyage home to New Zealand on Monday when France hands the mystic relic back more than a century after explorers took it away.

At the town hall in Rouen, northwest of Paris, Maori elders will perform chants, prayers and other rituals to honour the dead man, a relic of the ancient practice of mummification of Maoris killed in battle.

The head, which tribal custom forbids from being photographed or filmed, will be handed over to the Maoris in a box by officials from the town and the Museum of Rouen, which has housed it since 1875, organisers said.

Maoris will chant "invocations and solemn tributes to the dead warrior, who will be returned the very next day to his native land in order to find his final resting place," the museum said in a statement.

The restitution follows a four-year political struggle which ended last year when the French Senate voted a law allowing the return to New Zealand of all Maori human heads held in France, estimated to number between 12 and 15.

A computerised image of the Rouen head from the museum gives a haunting impression of a high cheekboned youth masked with swirling green tattoos, with a crooked-toothed grimace and a gruesome gash where one eye should be.

The ceremony was to be attended by New Zealand's ambassador to France, Rosemary Banks, and Michelle Hippolite, a director of the Te Papa museum in Wellington, herself a Maori, one of New Zealand's indigenous minority.

Experts there will carry out genetic tests on the head to try and identify its tribe of origin so it can be returned to its people and buried.

The story of how the head came to France is not known. It was given to the museum in 1875.

"It was exhibited until 1996 in the style of the 19th century, presented as a savage from the other side of the world, a survival from pre-historic times," said the Rouen museum's director Sebastien Minchin.

Rouen authorities decided to give the head back to the Maoris in 2007 but were overruled by the national government which feared setting a precedent for other museum holdings such as Egyptian mummies or relics of Christian martyrs.

The Senate made an exception for the Maori remains last year.

Maori warriors would tattoo their faces with elaborate geometric designs to show their rank. The recovered heads of those killed in battle were displayed and venerated until the soul was judged to have departed.

The tattoos made them an object of fascination for European explorers who collected and traded them from the 18th century onwards, prompting the macabre practice of tattooing and then killing slaves specially for their heads.

The first such head recorded as being acquired by a European was taken in 1770 by a member of an expedition of the British explorer James Cook. It was that of a 14-year-old boy believed to have been killed just for his head.

The demand for the preserved heads drove the true Maori to stop getting the tattoos and preserving their relatives' heads.

About 320 Maori heads have been returned from several countries since New Zealand began demanding their return in the 1980s, the organisers of Monday's ceremony said. The French museums are due to follow suit by 2012.

The organisers said a ceremony was also planned in New Zealand on May 12 to welcome the head home from Rouen.