The Trade and Investment Framework, which laid out ways to boost business but was not a fully-fledged deal, will remain suspended until democracy is restored, President Joe Biden's administration said.

"The United States strongly condemns the Burmese security forces' brutal violence against civilians," US Trade Representative Katherine Tai said, using Myanmar's former name of Burma.

"The killing of peaceful protesters, students, workers, labor leaders, medics and children has shocked the conscience of the international community," she said in a statement.

She said the United States would also scrutinize Myanmar's labor record as it determines tariff status, voicing "serious concerns" about the military's curbs on unions and worker rights.

The statement effectively removes Myanmar from the Generalized System of Preferences, in which the United State grants duty-free access to some imports from developing nations if they meet key standards.

The nearly 50-year-old program expired at the end of 2020 after lawmakers failed to act but Congress, controlled by Biden's Democratic Party, is widely expected to renew it soon.

Former president Barack Obama's administration reached the trade framework in 2013 and later added Myanmar to the list of countries with preferential trade access after a former junta transitioned to democracy.

The military on February 1 seized back control and arrested democratic leader Aung San Suu Kyi, sparking mass protests that troops have violently suppressed.

Biden has called the weekend bloodshed "absolutely outrageous" and has already imposed targeted sanctions on the junta.