"Secretary Pompeo raised the issue of two detained Reuters reporters with the Burmese foreign minister," State Department spokeswoman Heather Nauert said. "He said that they should be immediately released and expressed our concern about their ongoing detention."
Kyaw Soe Oo, 28, and his Reuters colleague, Wa Lone, 32, are facing up to 14 years in prison in Myanmar for allegedly violating the country's colonial-era Official Secrets Act. Both have pleaded not guilty to the charges and have told the court
how they were "trapped" by police officials who planted documents on them.
The trial has been adjourned until Monday, when the defense is expected to call character witnesses.
Myanmar government spokesman Zaw Htay, asked to comment on Pompeo's call for the reporters' release, said the case was already before the court.
"According to the constitution, our judiciary is independent so we must wait and see what the court decides," he told Reuters by phone. "Reuters and the families of the reporters are being treated equally under the law, with all the procedures being respected. For example, they can hire the lawyers they want."
At the time of their arrest in December, the journalists had been investigating the killing of 10 Rohingya Muslim men and boys in a village in western Myanmar's Rakhine state. The killings took place during an army crackdown that United Nations agencies say sent nearly 700,000 people fleeing to Bangladesh.
Pompeo and Kyaw Tin were asked by a reporter at the start of their meeting whether they would discuss press freedom and whether this was important to resolving the Rohingya issue. Neither replied.
Pompeo told a subsequent news conference that during the meeting of Association of Southeast Asian Nations (ASEAN) foreign ministers, the United States reaffirmed U.S. support for Myanmar's democratic transition but also "addressed the important steps required to resolve the continuing humanitarian crisis in the Rakhine state.
"Progress on these and other critical security issues is essential to a free and open Indo-Pacific," Pompeo said.
The United States has imposed sanctions on one Myanmar general, Maung Maung Soe, who was in charge of a crackdown on the Rohingya in Rakhine, after declaring that it constituted "ethnic cleansing", an accusation the Myanmar government denies.
The European Union and Canada have sanctioned more military figures.
The U.S. State Department did not immediately respond on Saturday when asked if the United States threatened any further action on Myanmar over the issue of the journalists or the wider Rohingya issue.
(Reporting by David Brunnstrom; Additional reporting by Antoni Slodkowski; Editing by Nick Macfie)