FISTON MAHAMBA and STANIS BUJAKERA  AN armed group in eastern Congo, accused by the government of carrying out an ambush on a United Nations convoy in which Italy's ambassador and two other people were killed, has denied any involvement in the attack. Congo's interior ministry on Monday blamed a Hutu militia called the Democratic Forces for the Liberation of Rwanda (FDLR), which is active near where ambassador Luca Attanasio, 43 and his bodyguard Vittorio Iacovacci, 30, were shot. World Food Programme driver Mustapha Milambo was also killed, local officials said. The FDLR was founded by senior Rwandan officers and militiamen…