This comes as State Counselor Aung Suu Kyi along with other top politicians were detained in the early hours of Monday, with Myanmar's military declaring a one-year state of emergency after weeks of escalating tensions over allegations of vote-rigging in the November election. The detentions and the seizure of power took place hours before the opening session of Myanmar's new Parliament.
All flights have been suspended and airports closed until May 31, The Myanmar Times reported citing the NOTAM.
In a statement issued by his spokesperson on Sunday, Secretary-General Antonio Guterres also voiced "grave concern" regarding the declaration of the transfer of all legislative, executive and judicial powers to the military.
"These developments represent a serious blow to democratic reforms in Myanmar," the statement said.
This military coup happened after days of escalating tensions between the government and the military in the aftermath of last November's general elections.
San Suu Kyi-led National League for Democracy (NLD) claimed an overwhelming victory in the polls, securing over 80 per cent of the seats, according to media reports. However, the military and some political parties disputed the results, alleging that the polls were marred by irregularities.
November's polls were only the second democratic elections in Myanmar since the end of nearly five decades of military rule. The first elections, in 2015, were also won by NLD.
According to media reports, the detentions started in the early hours of Monday (local time), with political leaders held in Yangon and other cities across Myanmar, and soldiers said to be out on the streets and at prominent landmarks.
Mobile phones, telephones and internet are also reported to have been cut in capital Nay Pyi Taw and the commercial hub of Yangon.
The military also imposed a state of emergency for a year, it announced on a military-run television station. According to media reports, other national and international television channels, and radio are offline.
A day after the military coup in Myanmar, all pilots have been instructed not to fly to and from the country without permission, according to a notice to airmen (NOTAM) issued on February 1.
The Myanmar Times reported that all previous permission and take off from the country has been revoked, including domestic and international relief flights.