The ambassador of the Democratic Republic of Italy was killed in an attack in the eastern part of the country, his foreign ministry said.
Luca Attanasio, 43, died in hospital on Monday after a fire broke out near Goma, the UN convoy he was traveling in, a statement said.
The caravan would be part of the United Nations World Food Program.
An Italian military policeman who was traveling with an ambassador and a Congolese driver were also killed.
With deep sadness, the Ministry of Foreign Affairs today confirmed the death of Italian Ambassador Goma, the ministry said in a statement.
The other two dead were 30-year-old military policeman Vittorio Ikovaci, who has worked at the embassy since September last year, and their Congolese driver, whose name has not yet been officially released.
Italian Prime Minister Mario Draghi made a statement deeply saddened, while President Sergio Materella condemned the cowardly attack.
Foreign Minister Luigi Di Maio expressed deep grief and deep sorrow at this brutal murder.
Italy today mourned the death of his two sons and embraced their families, saying, “No effort will be spared to shed light on what has happened.”
Officials from nearby Birunga National Park said the attack was a kidnapping attempt.
The bomber struck shortly after 10:15 a.m. local time near the town of Kanyahamhoro, just north of Goma, officials told Reuters.
It is not clear who was behind the attack, but several armed groups are said to have worked in and around the park.
Rome-based WFP said in a statement that Mr Atanasio came from Goma to watch a school program in the village of Rutshuru in eastern DR Congo.
There are frequent clashes between militias in the eastern part of the country, where a large UN force is fighting to keep the peace.
Mr Atanasio has been representing Italy in the DR Congo since 2013. He joined the diplomatic service in 2003. He spent his time in Morocco and Nigeria.
DR Congo has been at the center of a relentless civil war in several neighboring countries for years.
The conflict killed nearly five million people between 1994 and 2003, with some observers branded the Great War of Africa.
However, the end of the conflict did not end the violence. Dozens of militias and rebel groups remain active in the eastern region.
It has been part of the UN peacekeeping mission in DR Congo since 1999. It is one of the largest peace operations in the world, with more than 17,000 personnel on the ground.