The BBC's Fergal Keane returns to Rwanda: "This is a country where memory is poisoned by genocide"

The ceremony came shortly after three former ministers, implicated in the slaughter, were arrested in Cameroon where they fled after their regime was overthrown.

The men are said to have played key roles in the programme of murder, which resulted in more than 500,000 ethnic Tutsis and moderate Hutus being killed in 100 days.

The BBC's Jane Standley: "Rwanda is rebuilding its society"

In Kibeho, senior government figures, foreign diplomats and ordinary people attended a service inside the church where some of the killings took place.

Large coffins containing remains, exhumed from mass graves, were lowered into consecrated ground.

Some 20,000 victims were exhumed and reburied

Speakers including Rwandan President, Pasteur Bizimungu, called for reconciliation and justice in the country.

Rwanda has been in official mourning for the past week with flags flying at half mast and special programmes commemorating the genocide being shown across the country.

The genocide began on 6 April, 1994, just hours after a plane carrying President Juvenal Habyarimana, a Hutu, was shot down as it approached Kigali airport. The identity of the assailants remains unknown.

Hundreds of thousands were killed over the next 100 days before a Tutsi-led army seized power in July 1994.

Ministers named

UN officials said the three former ministers were arrested on Tuesday for their alleged role in the massacre.

They are former Foreign Minister Jerome Bicamumpaka and former Commerce Minister Justin Mugenzi, who allegedly played key roles in inciting the slaughter and justifying it to the outside world.

The third suspect is Prosper Mugiraneza, who ran Rwanda's civil service in the interim government set up in the first days of the genocide.

Ethnic hatred

Human rights groups have accused Mr Mugenzi of urging Hutus in a series of radio broadcasts to "kill all the Tutsis" and of travelling around the country stirring up ethnic hatred.

He also allegedly distributed machetes to local militiamen.

Mr Bicamumpaka defended the government before the UN Security Council, saying the violence was entirely the fault of Tutsi rebels.

Tribunal

The former ministers will be transferred to the UN's International Criminal Tribunal for Rwanda (ICTR) in Tanzania which is prosecuting the architects of the genocide.

The ICTR has already convicted three suspects, sentencing two of them to life and the other to 15 years.