Media reports say Myanmar's military has taken control of the country after detaining de-facto leader Aung San Suu Kyi and other politicians in the early hours.
According to the BBC, military TV said a state of emergency had been declared for one year and power transferred.
The coup comes after tensions rose between the civilian government and the military following a disputed election.
Myanmar, also known as Burma, was ruled by the military until democratic reforms began in 2011.
The military said on Monday it was handing power to commander-in-chief Min Aung Hlaing because of “election fraud.”
The coup has been widely condemned internationally, with the United States calling on Myanmar's military leaders to “release all government officials and civil society leaders and respect the will of the people.”
A statement released by White House spokesperson Jen Psaki on January 31, in particular, says “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 Counselor Aung San Suu Kyi and other civilian officials in Burma.”
US Secretary of State Antony Blinken called for the release of all government officials and civil society leaders and said the US "stands with the people of Burma in their aspirations for democracy, freedom, peace, and development. The military must reverse these actions immediately".
Australian Foreign Minister Marise Payne said “We call on the military to respect the rule of law, to resolve disputes through lawful mechanisms and to release immediately all civilian leaders and other who have been detained unlawfully.”
Singapore's Foreign Ministry urged all parties to exercise restraint and work towards a positive and peaceful outcome.
"We have noted the developments in Myanmar with deep concern. India has always been steadfast in its support to the process of democratic transition in Myanmar. We believe that the rule of law and the democratic process must be upheld," India's Ministry of External Affairs said in a statement.
UN Secretary-General Antonio Guterres “strongly” condemned the military's detention of Suu Kyi, President Win Myint and other leaders.
