President Barack Obama will press Myanmar leaders during an upcoming trip to restore calm to the western part of their country and bring instigators of ethnic violence there to justice, White House officials said on Thursday.

Obama leaves on Saturday for a trip to Asia that will include a historic stop in Myanmar, a former pariah state.

Some human rights workers object to the trip, saying the president is rewarding the country too soon for its still fragile democratic reforms.

Obama aides said the trip to the country was meant to lock in reforms and encourage more  while serving as an example to countries such as North Korea that the United States would engage with former foes if they reform.

But ethnic violence remains a top US concern. Tom Donilon, Obama's national security adviser, said the Myanmar government had taken constructive steps in restoring calm to areas of violence, allowing humanitarian access and pledging to bring perpetrators to justice.

"They need to follow through on each of these," Donilon said during a speech in Washington noting that US diplomats had been working closely with the government on how to proceed to ensure the safety of people in Rakhine State along Myanmar's western border.