BRUSSELS — Belgian prosecutors urged a court on Friday to impose a 30-year jail term on a former Rwandan official convicted of genocide for his part in his country's 1994 massacres.

Fabien Neretse, a 71-year-old agricultural engineer, was arrested in France in 2011 and was found guilty of genocide and war crimes on Thursday after a trial in the Brussels high court.

"Bear in mind the extreme gravity of the facts... this will to exterminate the other," prosecutor Arnaud D'Oultremont told the jury, branding Neretse "pitiless" in his targeting of Rwanda's Tutsi minority.

Neretse, who protested his innocence throughout the trial, is the first person to be convicted in Belgium on a genocide charge.

He was also convicted of war crimes for 11 killings in Rwanda, under Belgium's code of universal jurisdiction for the most serious offenses.

"You are sending a signal not only to Mr Neretse, but also the rest of the world," D'Oultremont said. "The signal will be clear; sir, madam, you will never sleep easy and Belgium will never be a land of impunity for genocidaires and war criminals.

"You'll never be welcome and we'll track you to the end," he said, stressing that Neretse had never admitted his crimes nor expressed regret.

Neretse remained passive in the dock during the sentencing hearing, just as he had while the verdict was read, but his lawyer continued to protest his innocence.

"My client will not confess because his it not guilty. The innocent do not confess," said defense counsel Jean Flamme, adding that for the elderly Neretse, a jail term would be "a slow, terrible death."

His defence hung on questioning the credibility of the multiple witnesses called against him — but prosecutors managed to prove that the exile has been living a lie for a quarter of a century.

Belgium has already held four trials and condemned eight perpetrators of killings in its former colony, but Neretse is the first defendant to be specifically convicted of the most grave charge — genocide.

During the trial, Neretse was accused of having ordered the murder of 11 identified civilians in Kigali and two in a rural area north of the capital in April and July 1994.

The jury cleared him of two of the Kigali killings, but found him guilty of 11 war crimes.

To demonstrate the more serious charge of genocide, the prosecutor cited Neretse's appearance at public rallies urging fellow members of the Hutu ethnic group to slaughter the minority Tutsi community.

Neretse was a farming expert who founded a college in his home district Mataba, in the north of Rwanda.

Between 1989 and 1992 he was director of the national coffee promoter, OCIR-Café, a key post in one of Rwanda's main export sectors.

He was seen as a local kingpin in Mataba, and a cadre in the former MRND ruling party of late president Juvenal Habyarimana.

But at trial he insisted he was an inactive party member and a friend to Tutsis.

"I will never stop insisting that I neither planned nor took part in the genocide," he insisted on Tuesday, before the jury retired to consider its verdict.

However, the court found there were many "improbabilities" in his statements, according to the judgement.

Neretse was arrested in France, where he had rebuilt a professional life as a refugee, and he has spent only a few months in protective pre-trial custody.

Under a 1993 law, Belgian courts enjoy universal jurisdiction to prosecute genocide, war crimes and crimes against humanity wherever they took place.

The case brought against Neretse was in large measure thanks to the determination of 70-year-old Belgian former EU civil servant Martine Beckers.

Beckers' sister, brother-in-law and 20-year-old niece were shot dead by a gang linked to Neretse.

Their killings took place three days after the assassination of Hutu president Habyarimana, the start of a genocidal campaign that would leave 800,000 Tutsis and moderate Hutus dead.

Beckers made a formal complaint to the Belgian federal police in 1994, and in the years since — working with Rwandan witnesses and human rights groups — she believes she has traced the instigators.

Magistrates have been compiling evidence in the case for 15 years. — AFP