Myanmar's 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 governing National League for Democracy said on Monday.

The move came 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.

Spokesman Myo Nyunt told Reuters by phone that Suu Kyi, President Win Myint and other leaders had been "taken" in the early hours of 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 that he expected to be arrested himself. Reuters was subsequently unable to contact him.

Phone lines to Naypyitaw, the capital, were not reachable in the early hours of Monday. Parliament had been due to start sitting there on Monday after a November election the NLD had won in a landslide.

A military spokesman did not answer phone calls seeking comment.

State-run MRTV television said in a Facebook post that it was unable to broadcast due to technical issues.

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.

Nobel Peace Prize winner 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.

The NLD won a landslide in last November's election, hammering a pro-military party.

Myanmar's military had said on Saturday it would protect and abide by the constitution and act according to law after comments earlier in the week had raised fears of a coup.

Myanmar's election commission has rejected the military's allegations of vote fraud, saying there were no errors big enough to affect the credibility of the vote.

The constitution reserves 25% of seats in parliament for the military and control of three key ministries in Suu Kyi's administration.