The United States has identified one person and it might impose sanctions on over the brutal crackdown in Myanmar against minority Rohingya Muslims and is examining others, US Secretary of State Rex Tillerson said on Friday.

Tillerson, who last month declared the violence against the Rohingya to be "ethnic cleansing," has said Washington was considering "targeted sanctions" against those deemed responsible.

More than 600,000 Rohingya Muslims have fled to southern Bangladesh since the end of August.

"We are continuing to examine the circumstances around all of the events since the August attacks that have led to the enormous migration of people out of Myanmar, and have already identified one individual and we are examining other possible individuals to hold responsible for targeted sanctions from the US," Tillerson told reporters at the United Nations.

US officials told Reuters that President Donald Trump's administration was considering only limited action at this stage. They said it was preparing narrow, targeted US sanctions against Myanmar's military and could roll out the punitive measures by year-end.

The sanctions will be aimed at increasing pressure on Myanmar authorities, but are not expected to hit the highest levels of the military leadership and will stop short of reimposing broad economic restrictions suspended under former President Barack Obama, according to the officials, who spoke on condition of anonymity.

The limited nature of any new sanctions is expected to be seen as little more than a warning for Myanmar and are not likely to satisfy international human rights groups and some US lawmakers who have accused Myanmar's armed forces of crimes against humanity.

Other world powers and the United Nations called Myanmar's campaign against the Rohingya population "ethnic cleansing" well before the United States did so in late November.

US OPTIONS MULLED

US officials in Washington and Yangon have been looking in particular at ways to use the Global Magnitsky Act, a law originally designed to target Russian human rights violators, but which has recently been expanded to allow sanctions for abuses anywhere in the world, the sources said.

That can take the form of US asset freezes as well as bans on travel to the United States.

A spokesman for the US State Department said the administration was in the final stages of preparing this year's Global Magnitsky report and had taken "an expansive view of implementation" of the act in the past year, but could not say when it might be delivered.

Myanmar's powerful army chief, General Min Aung Hlaing, is expected to be spared from the latest sanctions, according to three US officials and a congressional aide familiar with the matter.

In November, Myanmar's military said it had replaced Major General Maung Maung Soe, the general in charge in Rakhine state, but gave no reason for his transfer from a post as the head of the country's Western Command.

It was not immediately clear how far down the chain of command the US measures would reach and who might be named.

Two of the US officials said the Trump administration is considering only limited action at this stage to avoid upsetting the delicate political balance in Myanmar, where the civilian-led government headed by Nobel Peace Prize laureate Aung San Suu Kyi must still contend with an influential military.

Washington also wants to hold tougher options in reserve to escalate the US response if needed, the officials said.

Although the sanctions plan was still being finalized, the US officials said the aim was to roll it out before the end of December, possibly before Christmas, though one person close to the matter said an announcement could be delayed until early next year.

"We have nothing to announce on sanctions," a White House National Security Council spokesman said when asked the coming measures. He declined comment on who might be named.

Preparations for Myanmar sanctions come at the same time that Washington has expressed concern over the detention this week of two Reuters journalists.

Wa Lone and Kyaw Soe Oo had worked on stories about the military crackdown on the Rohingya population in Rakhine state.

Rohingya refugees in Bangladesh say their exodus from the mainly Buddhist country was triggered by a military offensive in response to attacks by Rohingya militant on security forces.

Washington has sought to balance its wish to nurture the civilian government in Myanmar, where it competes for influence with China, with its desire to hold the military accountable for the abuses.