By Aaron Ross and Clement Uwiringiyimana
KINSHASA/KIGALI (Reuters) - Democratic Republic of Congo has arrested a former Rwandan mayor accused of orchestrating the killing of tens of thousands of people during the 1994 genocide, Rwanda's prosecutor general said on Thursday.
Ladislas Ntaganzwa, who headed the commune of Nyakizu in southern Rwanda, was indicted in 1996 and is accused of genocide, direct and public incitement to commit genocide as well as extermination, murder and rape, Prosecutor General Richard Muhumuza said in a statement.
"The National Public Prosecution Authority is pleased to announce the recent arrest of Ladislas Ntaganzwa, one of the last fugitive suspects sought by the International Criminal Tribunal for Rwanda," Muhumuza said.
The tribunal's indictment, updated in 2012, accuses Ntaganzwa of plotting to exterminate Rwanda's Tutsi population and personally ordering the massacre of more than 20,0000 Tutsi civilians in one parish in April 1994.
The United States has offered up to $5 million for information leading to his arrest.
Ntaganzwa was arrested on Sunday in the town of Nyanzale in North Kivu province during an operation against the headquarters of the Democratic Forces for the Liberation of Rwanda (FDLR), a Rwandan Hutu militia, said Congo's army spokesman Leon Kasonga.
The FDLR is based in eastern Congo. Its leaders include senior figures in the genocide who fled into Congo after overseeing the slaughter of some 800,000 Tutsis and moderate Hutus in Rwanda between April and July 1994.
Ntaganzwa is not a member of the FDLR, the group's spokesman La Forge Fils Bazeye told Reuters.
In a statement on Thursday, the U.N. Mechanism for International Criminal Tribunals urged Congo to immediately transfer Ntaganzwa to Rwanda for trial.
Muhumuza said in his statement that Rwanda was prepared to prosecute Ntaganzwa before a specialised international crimes chamber of its High Court.
The Tanzania-based International Criminal Tribunal for Rwanda (ICTR) has convicted 61 people for involvement in the genocide, including leading military and government officials. New cases are expected to be heard by Rwandan courts or a separate tribunal backed by the United Nations.
Kasonga said Ntaganzwa is being held in the eastern city of Goma and would soon be transferred to the capital Kinshasa before any decision was made about extradition.
More than 20 years after the genocide, Rwanda is still pursuing perpetrators at home and internationally. Ntaganzwa is one of nine high-profile fugitives identified by the tribunal.