GENEVA, March 14 (Reuters) -Shortly after a massive bomb killed the U.N. envoy in Iraq Sergio Vieira de Mello in August 2003, his grieving widow and sons knew they wanted to perpetuate his life's work on behalf of victims of armed conflict. In an interview, Annie Vieira de Mello spoke of the strong idealism of the dashing Brazilian who worked in hotspots from Cambodia to Kosovo and Timor-Leste during his 30-year career with the United Nations.

Her husband -- tipped by some as a possible future U.N. Secretary-General -- was among 22 people killed when a truck loaded with explosives hit the Canal Hotel, the U.N. compound in Baghdad following the U.S.-led invasion of Iraq. She and their sons Laurent and Adrien were spending a summer day along Lake Geneva when word came of what is still the most deadly attack on the world body set up in 1945.

"As soon as the children and I received so many tributes and saw the outpouring of sympathy after the event, we thought he still had a role to play," Annie Vieira de Mello told Reuters at the U.N.'s European headquarters in Geneva, a hub for both humanitarian aid and human rights.

"It was the obvious thing to do, because when you are in mourning and pain, you want to try to hang onto those you've lost," the elegant French woman said quietly over tea. With friends and family, she set up a Swiss-based foundation to promote dialogue for peace in the name of her husband (www.sergiovdmfoundation.org).

Its patron, former U.N. Secretary-General Kofi Annan, will give the first annual Sergio Vieira de Mello memorial lecture in Geneva on Monday, two days after what would have been the 60th birthday of the slain U.N. envoy.

The foundation will award fellowships to young people whose families are caught up in war, as well as an annual prize in recognition of work to broker peace between parties to conflict.

"It could be a doctor or professor who takes political risks to encourage dialogue," said Annie Vieira de Mello, who is mobilising funds from U.N. agencies, governments, and private individuals for the awards.

"We hope my husband's name can bring international recognition and support that might protect this person and encourage him or her to continue," she said. Sergio was known for his efforts to promote understanding in difficult conditions.

He held talks with Palestinian leader Yasser Arafat while serving in the U.N. Interim Forces in Lebanon in the early 1980s, and successfully sought a decade later to help resolve the fate of Vietnamese boat people.

"He was a man of action, of negotiations, who liked meeting people and trying to understand conflicts," his widow said. "He liked to bring people together to find a solution, which is why the foundation is based on the idea of dialogue between communities in conflict."

(Editing by Laura MacInnis and Paul Casciato)