Myanmar's de-facto leader Aung San Suu Kyi issued a pre-emptive call for people to reject any coup, before she was detained by the military on Monday, her party said.
Suu Kyi called on people "not to accept a coup", according to a post on the official Facebook page of the chair of the National League for Democracy.
Myanmar's military has put the country under a state of emergency for a year.
Suu Kyi's message reiterated the National League for Democracy's landslide victory in the November 2020 election.
The Facebook post noted the military's actions could jeopardise the country's efforts to fight a coronavirus outbreak.
Myanmar has registered more than 140,000 cases and more than 3,000 deaths.
The post said she had not accepted a controversial army-scripted 2008 constitution, but had abided by it since entering parliament.
The constitution carved out a powerful ongoing political role for the military, giving them control of the key interior, border and defence ministries and a bloc of parliamentary seats.
Suu Kyi and her government had been trying to amend the charter since winning the 2015 election, with little success.
During the last term, she circumvented a constitutional clause that prevented her from assuming the presidency by taking the de facto leadership role of "state counsellor".