Obama was set to raise powderkeg rights issues in a meeting with his Myanmar counterpart Thein Sein - a former general turned reformer - late today on the sidelines of the East Asia Summit in Myanmar's capital, Naypyidaw.
Obama set the tone for his meeting with hard-hitting comments on the pace of reforms in an interview with Myanmar news website The Irrawaddy published just before he arrived last night for a three-day trip.
"Even as there has been some progress on the political and economic fronts, in other areas there has been a slowdown and backsliding in reforms.
"In addition to restrictions on freedom of the press, we continue to see violations of basic human rights and abuses in the country's ethnic areas, including reports of extrajudicial killings, rape and forced labour."
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Around 140,000 Rohingya languish in fetid displacement camps in western Rakhine State after religious violence flared two years ago, leaving scores of the minority dead and casting a dark cloud over the nation's pathway towards democracy.
United Nations Secretary-General Ban Ki-moon yesterday also raised the "serious humanitarian" condition of the Rohingya.
Obama met opposition leader and Democracy champion Aung San Suu Kyi this afternoon at discussions with a group of lawmakers in the capital.
Suu Kyi had preceded Obama's trip with her own warning against "over-optimism" about democracy in Myanmar, as the nation heads for crucial general elections next year.
She is campaigning to change the junta-era constitution, which currently bars her from the presidency - even if her party is successful in the polls - and earmarks a quarter of the legislature for unelected soldiers.