U.N. Secretary-General Ban Ki-moon started his two-day trip to the small, half-island nation by meeting with President Taur Matan Ruak, the former army chief and one-time guerrilla fighter who took office May 20 and replaced Nobel Peace Prize laureate Jose Ramos-Horta.
The visit comes after the U.N. Security Council praised the country of 1.1 million people for holding peaceful presidential elections.
Protests after last month's parliamentary elections resulted in violence that left one dead. But Asia's poorest country is now planning for the last of nearly 1,300 international peacekeepers to leave by year's end.
"Timor-Leste does not need U.N. peacekeeping operations at this time," Ban said in the capital, Dili. "The National Police of Timor-Leste have strengthened their capacity. They have successfully helped the three rounds of parliamentary and presidential elections."
He added that the United Nations would stay in East Timor in other capacities.
A Portuguese colony for three centuries, East Timor voted in 1999 to end 24 years of brutal Indonesian occupation that left more than 170,000 dead. Withdrawing Indonesian troops and proxy militias killed 1,500 people and destroyed much of the country's infrastructure.
"All the perpetrators for the crimes against humanity and war crimes must be brought to justice," Ban said, adding he and Ruak discussed the issue. "I know that according to our experience, political stability cannot be sustainable when there is no justice for the crimes against (a) civilian population."
Formal independence was declared in May 2002, and the international community invested billions of dollars and deployed U.N. peacekeepers to help stabilize the new democracy. But extreme poverty, gang violence and disputes between the military and police resulted in the government's collapse in 2006.