A military coup was taking place in Myanmar early Monday and State Counsellor Aung San Suu Kyi was detained under house arrest, reports said, as communications were cut to the capital.

Phone and internet access to Naypyitaw was lost and Suu Kyi’s National League for Democracy party could not be reached.

The US, Australia and others were concerned by the reports and urged Myanmar’s military to respect the rule of law.

“The United States is alarmed by reports that the Burmese military has taken steps to undermine the country’s democratic transition, including the arrest of State Counsellor Aung San Suu Kyi and other civilian officials in Burma,” White House spokesperson Jen Psaki said in a statement from Washington. She said President Joe Biden had been briefed on the reported developments.

“The United States opposes any attempt to alter the outcome of recent elections or impede Myanmar’s democratic transition, and will take action against those responsible if these steps are not reversed,” the statement said. Burma is the former name of Myanmar.

Australian Foreign Minister Marise Payne called for the release of Suu Kyi and others reported to be detained. “We strongly support the peaceful reconvening of the National Assembly, consistent with the results of the November 2020 general election,” she said.

Myanmar lawmakers were to gather Monday in the capital Naypyitaw for the first session of Parliament since last year’s election.

Online news portal Myanmar Now cited unidentified sources about the arrest of Suu Kyi and the NLD’s chairperson around dawn and did not have further details. Myanmar Visual Television and Myanmar Voice Radio posted on Facebook around 6:30 a.m. that their programs were not available to broadcast regularly.

The 75-year-old Suu Kyi is by far the country’s most dominant politician, and became the country’s leader after leading a decades-long nonviolent struggle against military rule.

Suu Kyi’s party captured 396 out of 476 seats in the combined lower and upper houses of Parliament