A Hutu rebel group, known as the Democratic Forces for the Liberation of Rwanda (FDLR), has denied any role in Monday's killing of Italy's ambassador to the Democratic Republic of Congo.
Luca Attanasio, 43, died in hospital after the United Nations convoy he was travelling in came under fire near the eastern town of Goma.
An Italian military police officer travelling with the envoy and a Congolese driver were also killed.
DR Congo's interior ministry accused the FDLR rebel group of being behind the attack
But the group's spokesman has denied the accusation.
“More than 100 armed groups operate here, we don’t know why
Mr Ngoma said that “whoever will be identified as responsible for the attack should be severely punished”.
In a statement, the armed group said the attack happened in an area where both DR Congo and Rwanda had a military presence – so any investigation should take that into account.