Myanmar's military stepped up its crackdown on democratic leaders as Win Htein, senior leader of the National League for Democracy party, said he was arrested under sedition laws.
Htein is one of the other National League leaders including leader Aung San Suu Kyi who was held by the military earlier last week.
Htein's arrest was carried out before dawn Friday. He was able to make a call to BBC Burmese. He said police and military officials came to take him to the capital. "They are afraid of what I'm saying," Htein said.
National League press officer Kyi Toe said Htein was taken from his daughter's house in Yangon and was detained at a police station in Naypyidaw.
Before his arrest, Htein had spoken against the coup. He is recognized in the country as a solid supporter of Suu Kyi and the latter's right-hand man.
According to Htein, he was not provided with the details of the charges that he was being accused of under sedition laws.
Aside from Htein, Yangon-based group that monitors political arrests in the country, Assistance Association for Political Prisoners, there are more than 130 other politicians and public officials who were detained since Monday.
Shortly after news of the coup spread Htein encouraged Myanmar to oppose the military's actions "as much as they can." He also said the coup was "not wise."
Since the coup, there has been worldwide concern from leaders, democracy advocates and a growing group of people in Myanmar who supported Suu Kyi's government.
Facebook has been blocked in the country, hampering communication for many.
U.S. President Joe Biden and other leaders have also supported Suu Kyi, with Biden calling on the military led by Min Aung Hlaing to "relinquish power" and release those who were detained.
There have been no protests or rallies but some groups have started expressing hints of opposition against the military.
In particular, more than 1,000 doctors across 70 hospitals in the country went on strike to protest the coup. Mobile phone connections were interrupted at the peak of the strike but were restored later in the day.
Some employees of other industries have said they will not support the coup and are missing work. A primary school teacher said the "dictatorship must fall."
A growing number of liquor store owners in Yangon have stopped selling products that had links to military-related companies. Residents in the town also made noise throughout Tuesday and Wednesday by banging pots and pans.
Since Suu Kyi and President Win Myint were arrested, the two have not been spotted in public. Suu Kyi's detainment marked the end of a decade of Myanmar's democracy after many difficult years under military junta jurisdiction.
