KIGALI (AFP) - United Nations Secretary-General Ban Ki Moon said on Monday that the world body was still wracked by shame over its failure to act against the genocide in Rwanda 20 years ago.

"Many United Nations personnel and others showed remarkable bravery. But we could have done much more. We should have done much more. In Rwanda, troops were withdrawn when they were most needed," Mr Ban said in a speech at commemorations marking the 20th anniversary of the genocide.

"One year later in Srebrenica, areas proclaimed 'safe' by the United Nations were filled with danger, and innocents were abandoned to slaughter," he added, saying: "The shame still clings, a generation after the events."