Myanmar leader Aung San Suu Kyi and other senior figures from the ruling party have been detained in an early morning raid, the spokesman for the country’s governing National League for Democracy says.

The pre-dawn move on Monday followed 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.

Spokesman Myo Nyunt told Reuters by phone that MS Suu Kyi, President Win Myint and other leaders had been “taken” early in the morning.

“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.

Phone lines to Naypyitaw, the Myanmar capital, were not working early on Monday.

A military spokesman did not answer phone calls seeking comment.

An NLD lawmaker, who asked not to be named for fear of retaliation, said another of those detained was Han Thar Myint, a member of the party’s central executive committee.

Military officials on Sunday denied their chief had threatened to stage a coup over complaints of election fraud, saying the media had misinterpreted his words.

Political tension soared last week after a spokesman for the military, which ruled Myanmar for five decades, said a coup could not be ruled out if its complaints of widespread fraud in November’s election were ignored.

The commander-in-chief, Senior General Min Aung Hlaing, told senior officers in a speech Wednesday the constitution could be revoked if the laws were not being properly enforced.

Adding to the concern was the unusual deployment of armoured vehicles in the streets of several large cities.

Saturday’s statement from the military, known as the Tatmadaw, said “some organisations and media” wrote without foundation that the military had threatened to revoke the constitution.

The statement said Min Aung Hlaing’s speech was taken out of context and was actually an observation to senior officer trainees on the nature of the constitution.

The ruling National League for Democracy party captured 396 out of 476 seats in the November 8 election, allowing it to form a government led by Ms Suu Kyi for another five years.

The military-backed Union Solidarity and Development Party won only 33 seats.

The military has publicly complained several times of mass electoral fraud and called for an official review of the results.