President Joe Biden said Wednesday the United States was taking action against Myanmar's military including freezing access to US-based assets as he urged its generals to relinquish power.

"Today I again call on the Burmese military to immediately release democratic political leaders and activists they are now detaining including Aung San Suu Kyi and also Win Myint, the president," Biden said in his latest remarks following last week's coup.

"The military must relinquish power," he said.

Biden said that his administration was cutting off the generals' access to $1 billion in funds in the United States and would soon unveil new sanctions.

"I've approved a new executive order enabling us to immediately sanction the military leaders who directed the coup, their business interests as well as close family," Biden said.

Biden said that his administration would identify the first round of targets under the sanctions this week.

He reiterated that the United States would not curb assistance to Myanmar, also known as Burma, directed toward civil society or humanitarian groups.

US law forbids assistance to governments that take power in coups, although virtually all US funding to Myanmar is channelled through non-governmental groups.

Top generals including the army chief who led the coup, Min Aung Hlaing, are already under US travel and financial sanctions for Myanmar's brutal campaign against the mostly Muslim people Rohingya people.

State Department spokesman Ned Price said that the United States could still raise further pressure on the generals by coordinating its action with allies. "We can impose costs that are even steeper by working with our like-minded partners and allies," Price said.