Gibril Massaquoi, a Sierra Leonean living in Finland since 2008, is accused of murder, aggravated war crimes and aggravated crimes against humanity during the West African country's internal conflict a generation ago.

Allegedly known by the moniker "Angel Gabriel", the 51-year-old appeared before the Pirkanmaa District Court in Tampere, the Finnish town where he was arrested in March last year.

In a historic first, the court will also move to Liberia and neighbouring Sierra Leone in mid-February to hear testimony from up to 80 witnesses and visit sites where the atrocities allegedly unfolded under Massaquoi's orders.

Wearing a grey suit and facemask, Massaquoi listened through a translator as prosecutor Tom Laitinen read the charges: a grisly litany of killings, rapes and torture the prosecution says were carried out by Massaquoi and soldiers under his command between 1999 and 2003.

He faces a life sentence, which in Finland means on average 14 years behind bars.

Court documents seen by AFP contend that Massaquoi held an "extremely senior and influential position" in the Revolutionary United Front (RUF), one of the main militias fighting alongside then-president Charles Taylor's NPFL forces.

Finnish law allows the prosecution of serious crimes committed abroad by a citizen or resident.

- 'Groundbreaking' trial -

In the northern Liberian village of Kamatahun Hassala, witnesses say Massaquoi ordered civilians, including children, to be locked into two buildings which were then torched.

At least seven women were raped and murdered in the village and other locals were killed, their bodies cut up and "made into food which Massaquoi also ate," Laitinen told the court.

The 4,000-page evidence dossier further details mass murders and rapes in Lofa county and the capital Monrovia, and accuses Massaquoi of enslavement and using child soldiers.

The crimes "deliberately and systematically" violated international humanitarian law, and inflicted "irreparable emotional suffering and damage" on the families of his many victims, prosecutors wrote.

Massaquoi insists he was involved in peace negotiations elsewhere in the region at the time of the atrocities.

"He hasn't been in the places where these offences took place, he has not been in Liberia after June 2001," defence lawyer Paula Sallinen told AFP, welcoming the opportunity to hear witnesses in Liberia and Sierra Leone.

News that the court will sit in Liberia has also been welcomed in the country whose back-to-back civil wars between 1989 and 2003 left 250,000 people dead and millions displaced.

"This is a good step taken by the international community. It is a signal that crimes committed during the civil war will not go unpunished," human rights activist Adama Dempster told AFP in Monrovia.

Civitas Maxima, a rights group whose probe into Massaquoi prompted Finnish police to act, said the "groundbreaking" decision could set "a monumental precedent".

So far only a handful of people have been convicted for their part in the conflict, and efforts to establish a war crimes court in the country have stalled.

Former Liberian warlord-turned-president Taylor was imprisoned in 2012 -- but for war crimes committed in neighbouring Sierra Leone, not in his own country.

- 'Nothing left behind' -

Laitinen praised the "extraordinary" efforts by Finnish police to gather testimony in situ.

"They took the bull by the horns and went to Liberia, first of all to negotiate with the Liberian authorities for permission to investigate, then they just went out into the jungle and investigated," he told AFP.

The Finnish trial has thus avoided the problems of bringing witnesses to Europe that have hampered ongoing Liberian war prosecutions in Switzerland and France.

"I welcome the trial and it's our prayers that the court opens in Liberia," survivor Alexander Fayiah told AFP.

Now 42, Fayiah said he was 12 when RUF fighters stormed his village of Foyah in Lofa county, and his mother managed to smuggle him away to safety.

"When they left, there was nothing left behind. Houses were burnt, women were raped and kids were taken hostage to become child soldiers," Fayiah said.

Massaquoi was allowed to relocate to Finland in return for giving evidence to the UN-led Special Court for Sierra Leone in 2003, set up to examine that country's civil war.

He received immunity from prosecution over acts committed in Sierra Leone, but not in Liberia.

After approximately 10 weeks in Africa, the case will continue until June, with a verdict in September.