PHNOM PENH, Cambodia — President Obama on Monday became the first sitting US president to visit Cambodia, arriving to little fanfare and then pointedly criticizing the country’s autocratic leader on the issue of human rights during a tense meeting.
The meeting came hours after Obama was cheered by massive flag-waving crowds in Myanmar, a long-isolated country to which he offered a ‘‘hand of friendship’’ as it rapidly embraces democratic reforms.
Obama was an early champion of Myanmar’s sudden transformation to civilian rule after a half-century of military dictatorship. He has rewarded the country, also known as Burma, with eased economic penalties, increased US investment and now a presidential visit, in part to show other nations the benefits of pursuing similar reforms.
‘‘You’re taking a journey that has the potential to inspire so many people,’’ Obama said during a speech at Myanmar’s University of Yangon.
The Cambodians are among those Obama is hoping will be motivated.
White House officials said he held up Myanmar, a once-pariah state, as a benchmark during his private meeting Monday evening with Prime Minister Hun Sen, who has held power in Cambodia for nearly 30 years.
Unlike the arrangement after Obama’s meetings with Myanmar’s president, Thein Sein, and democracy leader Aung Sun Suu Kyi, the US and Cambodian leaders did not speak to the press after their one-on-one talks. They did step in front of cameras briefly before their meeting to greet each other with a brisk handshake and little warmth.
In private, US officials said, Obama pressed Hun Sen to release political prisoners, stop land seizures, and hold free and fair elections. Aides acknowledged the meeting was tense, with the Cambodian leader defending his practices, even as he professed to seek a deeper relationship with the United States. Ben Rhodes, Obama’s deputy national security adviser, said the president told Hun Sen that without reforms, Cambodia’s human rights woes would continue to be ‘‘an impediment’’ to that effort.
White House officials emphasized that Obama would not have visited Cambodia had it not been hosting two regional summit meetings the United States attends, a rare admonishment of a country on its own soil.
The Cambodian people appeared to answer Obama’s cold shoulder in kind. Just a few small clusters of curious Cambodians gathered to watch his motorcade speed though the streets of Phnom Penh.
Obama talked on the sidelines of the East Asia Summit with Prime Minister Yoshihiko Noda of Japan. Briefly addressing reporters before the private meeting, Obama called the relationship between the United States and Japan a ‘‘cornerstone of prosperity and security in the region.’’ The two leaders were set to discuss jobs, trade, and the economy.
Obama was also due to meet with Wen, the Chinese premier.
Human rights groups fear that because Obama delivered his condemnation of Hun Sen in private, government censors will keep his words from reaching the Cambodian people. And they worry the prime minister will then use Obama’s visit to justify his grip on power and weaken the will of opposition groups.
‘‘If Hun Sen’s narrative about this visit is allowed to jell, it will create a perception that the United States and other international actors stand with Hun Sen, and not with the Cambodian people,’’ said John Sifton, Asia director at Human Rights Watch.
Hun Sen, 60, has held power since Ronald Reagan was in the White House, and says he will not be stepping down until he is 90. He is known as one of Asia’s most opportunistic politicians, with a knack for making sure his rivals end up in jail or in exile.
Over the last decade, he has overseen modest economic growth and stability in a country plagued by desperate poverty and nearly destroyed under the Khmer Rouge ‘‘killing fields’’ regime.
Obama’s visit to Myanmar was also viewed critically by some international organizations, which saw the trip as a premature reward for a country that still holds political prisoners and has been unable to contain violence.