French police arrested one of the last key suspects sought over the Rwandan genocide on Saturday, prosecutors and police said.

Felicien Kabuga, once one of Rwanda's richest men and accused of financing the genocide, was living under a false identity in the French capital's suburbs, the public prosecutor's office and the police said in a joint statement.

"Felicien Kabuga is known to have been the financier of the Rwandan genocide," it said, adding that he had spent time in Germany, Belgium, the Democratic Republic of Congo, Kenya and Switzerland.

A top UN prosecutor welcomed the arrest, saying it showed that suspects would be brought to justice for crimes in the 1994 genocide.

"The arrest of Felicien Kabuga today is a reminder that those responsible for genocide can be brought to account, even 26 years after their crimes," said Serge Brammertz, chief prosecutor of the Mechanism for International Criminal Tribunals in The Hague.