“State Counsellor Daw Aung San Suu Kyi and some other senior figures are being detained in Nay Pyi Taw,” spokesman Myo Nyunt said.
The move comes after days of escalating tension between the civilian government and the powerful military, in the aftermath of an election the army says was fraudulent, Reuters reported.
“We oppose any attempt to alter the outcome of the elections or impede Myanmar’s democratic transition,” said the statement, which was signed by missions from the US, the UK and the European Union.
“We support all those who work toward greater democratic freedoms, lasting peace, and inclusive prosperity for the people of Myanmar.”
Since her party won a landslide victory in 2015, she has been Myanmar’s de facto leader and held the position of state counsellor — a title invented as a loophole to the constitution barring her from becoming president.
But her international reputation has been tarnished in recent years by allegations of genocide against the Myanmar’s Muslim Rohingya population.
Myanmar denies the charges and has long claimed to have been targeting terrorists.