The United States threatened to reimpose sanctions on Myanmar's generals after they seized power in a coup and detained elected leader Aung San Suu Kyi, whose whereabouts remained unknown on Tuesday more than 24 hours after her arrest.

The UN Security Council was due to meet later on Tuesday, diplomats said, amid calls for a strong global response to the military's arrest of the Noble Peace laureate and dozens of her political allies on dawn raids on Monday.

The coup followed a landslide win for Suu Kyi's National League for Democracy (NLD) party in November elections, a result the military has refused to accept citing allegations of fraud.