Myanmar’s military declared a one-year state of emergency on Monday and appointed a general as acting president, after arresting civilian leader Aung San Suu Kyi and other senior officials.
An announcement read out on military-owned Myawaddy TV said the move was needed to preserve the "stability" of the state, accusing the country’s election commission of failing to address "huge irregularities" in the November election.
"The UEC (election commission) failed to solve huge voter lists irregularities in the multi-party general election which was held on Nov 8, 2020," said the statement signed by the new acting president Myint Swe, a former general who had been vice-president.
The statement accused "other party organisations" of "harming the stability of the state", reports The Straits Times.
"As the situation must be resolved according to the law, a state of emergency is declared."
The statement said responsibility for "legislation, administration and judiciary" had been handed over to military commander-in-chief Min Aung Hlaing.
The move comes hours after Ms Suu Kyi and other senior figures from the ruling National League for Democracy (NLD) party were detained in an early morning raid.
It also comes after days of escalating tension between the civilian government and the powerful military that stirred fears of a coup in the aftermath of an election the army says was fraudulent.
NLD spokesman Myo Nyunt told Reuters by phone that Ms Suu Kyi, President Win Myint and other leaders had been "taken" in the early hours of the morning.
"With the situation we see happening now, we have to assume that the military is staging a coup," he said.
"I want to tell our people not to respond rashly and I want them to act according to the law," he said, adding he also expected to be detained.
Reuters was subsequently unable to contact him.
The Myanmar army said it had carried out the detentions in response to "election fraud", according to a statement on a military-owned television station.
Phone lines to the capital Naypyitaw were not reachable and state TV went off air hours before Parliament had been due to sit for the first time since the NLD’s landslide election win in November, viewed as a referendum on Ms Suu Kyi’s fledgling democratic government.
Soldiers took up positions at city hall in the main city of Yangon, and mobile Internet data and phone services in the NLD stronghold were disrupted, residents said.
Internet connectivity had also fallen dramatically, monitoring service NetBlocks said.
An NLD lawmaker, who asked not to be named for fear of retaliation, said another of those detained was Mr Han Thar Myint, a member of the party’s central executive committee.
Elsewhere, the chief minister of Karen state and several other regional ministers were also held, according to party sources.
Nobel Peace Prize winner Ms Suu Kyi, 75, came to power after a 2015 landslide election win that followed decades of house arrest in a struggle for democracy that turned her into an international icon.
Her international standing was damaged after hundreds of thousands of Rohingya fled army operations into refuge from Myanmar’s western Rakhine state in 2017, but she remains hugely popular at home.
Political tensions soared last week when a military spokesman declined to rule out a coup ahead of the new Parliament convening on Monday, and Senior General Min Aung Hlaing raised the prospect of repealing the Constitution.
Myanmar has seen two coups since independence from Britain in 1948 - one in 1962 and one in 1988.
But the military appeared to backtrack on the weekend, issuing a statement on social media on Sunday saying it would "do everything possible to adhere to the democratic norms of free and fair elections".
Tanks were deployed in some streets last week and pro-military demonstrations have taken place in some cities ahead of the first gathering of Parliament.