Four people, including two pro-democracy activists, have been executed in Myanmar, the military government said Monday, drawing swift international condemnation, including from Japan, as the junta continues to rule the Southeast Asian country following a February 2021 coup.

There had been no executions of political prisoners in Myanmar since the 1970s, and the most recent instance of capital punishment was carried out in 1990, according to local media.

The four included two political prisoners -- Phyo Zeyar Thaw, 41, a former National League for Democracy lawmaker, and Kyaw Min Yu, 53, a prominent pro-democracy activist widely known as Jimmy.

Military tribunals had sentenced the two to death in January for their involvement in "terror acts" that included murder. The other two, U Hla Myo Aung and U Aung Thura Zaw, were reportedly implicated in the killing of a woman who was an alleged military informant.

People stage a rally in Yangon, Myanmar, on Feb. 22, 2021, in protest against the Feb. 1 military coup. (Kyodo)

The United Nations, European countries and the United States, as well as Cambodian Prime Minister Hun Sen, who serves as this year's chairman of the Association of Southeast Asian Nations, had called for the junta not to carry out the executions.

The executions "completely go against the 'release of the detainees,' which Japan has consistently called for," Japanese Foreign Minister Yoshimasa Hayashi said in a statement.

The move will "lead to deeper conflict due to the hardening of public sentiment and further isolation of Myanmar from the international community," Hayashi added.

U.S. Secretary of State Antony Blinken said in a statement his government "condemns in the strongest terms" the executions of the four individuals for the exercise of their "fundamental freedoms," adding that the Myanmar regime's "sham trials and these executions are blatant attempts to extinguish democracy."

State Department spokesman Ned Price told a press conference that "there can be no business as usual" with Myanmar's junta and urged all countries to ban the sale of military equipment to the country and to refrain from lending the regime "any degree of international credibility."

Phyo Zeyar Thaw was a close aide to now-jailed national leader Aung San Suu Kyi, who led the pro-democracy party until the military deposed the NLD-led democratically elected government on Feb. 1, 2021.

Phyo Zeyar Thaw and Kyaw Min Yu were purportedly in touch with the National Unity Government, a group set up by pro-democracy forces as a shadow government. The military has designated the group a "terrorist organization."

Duwa Lashi La, the NUG's vice president who serves, in effect, as its leader, condemned the executions on Twitter, calling on the United Nations and the international community to take action.

The NLD said in a statement, "We bow and honor the martyrs who were mercilessly murdered by the military gang of terror," and denounced the executions as another outrageous crime by the junta on top of the countless atrocities it has already committed.

On social media, many Myanmar users have changed their profile pictures to plain black to mourn the deaths of the pro-democracy activists.

According to the online local media Myanmar Now, the families of the four inmates had an online meeting with them at Insein Prison in Yangon on Friday.

Kyaw Min Yu appeared in good health and told his family, "Don't worry. Everyone has his own share of Karma," the report said, citing a prison source.

The four were hanged the following morning, and their bodies were cremated by the end of the day, according to the report.

Phyo Zeyar Thaw was a member of a popular hip-hop group before becoming a lower house member. Kyaw Min Yu was a leader of the 1988 pro-democracy movement.

Since the coup, 117 people have been sentenced to death in Myanmar, including in absentia, according to the Assistance Association for Political Prisoners, a rights group monitoring the situation in the country.

Myanmar courts are now under military control, and court hearings have been closed to the public, leading critics to question the impartiality of the judicial process.

Yuyun Wahyuningrum, a human rights activist and an Indonesian representative to the ASEAN Intergovernmental Commission on Human Rights, a consultative body of the regional group, said Myanmar would have breached the ASEAN Human Rights Declaration by reportedly not allowing the four people to have legal counsel during the trial and executing them.

The declaration was adopted by ASEAN member states, including Myanmar, in 2012.

Regional director of Amnesty International, Erwin van der Borght, also said the military court convicted the four men in highly secretive and deeply unfair trials.

Suu Kyi, the democracy icon who won the 1991 Nobel Peace Prize, was detained following the coup. She has so far been sentenced to more than 10 years in prison for corruption and other charges. The military said in late June that she has been imprisoned in the capital Naypyitaw.

Long under a military government, Myanmar began transitioning to civilian rule in 2011. The NLD first came to power in 2016 after the 2015 general election. It maintained control in the general election in November 2020.

But just before elected NLD members were to sit in parliament, the military seized power, reversing a decade of progress toward democracy.

Meanwhile, China, which has refrained from condemning the Myanmar military since the coup in an apparent attempt to increase its economic and security influence in the neighboring country, avoided commenting directly on the executions.

Chinese Foreign Ministry spokesman Zhao Lijian told reporters Monday that China adheres to the principle of noninterference in other countries' internal affairs.

Price said the United States is urging "all countries" to act in a way that would ultimately put Myanmar back on the path to democracy, noting that "no country has the potential to influence the trajectory" of the Southeast Asian nation "more so than China."