It is believed that it is the first time capital punishment was used in the country after decades.

Former lawmaker Phyo Zeya Thaw, writer and activist Ko Jimmy, Hla Myo Aung and Aung Thura Zaw were accused of committing "terror acts", BBC reported.

Reacting to the development, Human Rights Watch said it opposes capital punishment in all countries and under all circumstances because of its inherent cruelty and finality, and has long called on Myanmar to end all use of the death penalty.

“The Myanmar junta’s execution of four men was an act of utter cruelty,” said Elaine Pearson, acting Asia director at Human Rights Watch. “These executions, including of activist Ko Jimmy and opposition lawmaker Phyo Zeya Thaw, followed grossly unjust and politically motivated military trials. This horrific news was compounded by the junta’s failure to notify the men’s families, who learned about the executions through the junta’s media reports.

“The junta’s barbarity and callous disregard for human life aims to chill the anti-coup protest movement. European Union member states, the United States, and other governments should show the junta that there will be a reckoning for its crimes. They should demand immediate measures, including the release of all political prisoners, and let the junta know the atrocities it commits have consequences.”

Tom Andrews, the U.N. special rapporteur on human rights in Myanmar, tweeted: " I'm devastated by news that former parliamentarian Zeyar Thaw and longtime activist Ko Jimmy were executed with two others today. UN Member States must honor their lives by making this depraved act a turning point for the world's response to this crisis."