(CNN) -- The U.N. chief made a landmark visit to Myanmar on Sunday, the latest high-profile official to descend on the nation as it undergoes economic and political reforms.
Secretary-General Ban Ki-moon arrived during the day in Yangon, disembarking from a U.N.-designated plane to greet a number of people including Myanmar Foreign Minister Wunna Maung Lwin.
Ban is set to meet President Thein Sein and Aung San Suu Kyi, the pro-democracy leader who was subject to house arrest for years but recently won a seat in Myanmar's parliament.
Speaking last week, Ban had said his visit comes at a "critical moment" for the South Asian nation, which is also known as Burma.
"Myanmar is only at the beginning of its transition," Ban said then. "Many challenges lie ahead. Many concerns have yet to be addressed. Yet I am convinced that we have an unprecedented opportunity to help the country advance toward a better future."
The government's relationship with the international community is thawing after it started implementing economic reforms and opened up dialogue with the West and ethnic minority rebel groups.
Ban applauded several recent reforms, including elections and steps toward reconciliation with the rebels and opposition movements. But he said more needs to be done.
"Now is the time for the international community to stand together at Myanmar's side," he said. "Yet we also recognize this fresh start is still fragile."
The trip, which follows a series of political reforms in Myanmar, marks the latest step in the country's international rehabilitation after decades of isolation.
European Union foreign policy chief Catherine Ashton met with Suu Kyi on Saturday.
Ashton will open a new embassy-level office for the European Union in Yangon to "help support Myanmar/Burma on its path to full democracy."
Myanmar's authoritarian military rulers are loosening their grip on power after decades of stifling dissent and limiting freedoms.
In the past 12 months, the government has pardoned hundreds of political prisoners, secured a cease-fire with Karen rebels and agreed to negotiate with other ethnic rebel groups.
Suu Kyi and 42 other candidates from her party won seats in elections on April 1, a result welcomed by the United States and Britain as a sign of progress toward democracy after decades of repressive military rule.
After the elections, Suu Kyi and other newly elected opposition members were invited to attend a parliament session last week, but they demurred, requesting a change in the wording of the lawmakers' oath.
The tension over the oath marks the first public sign of conflict between the opposition and the reformist government since the elections.
Other high-profile visitors to Myanmar in recent months include British Prime Minister David Cameron and U.S. Secretary of State Hillary Clinton.