A Japanese video journalist has been detained by security forces in Myanmar while covering a protest against military rule in the country's largest city, pro-democracy activists said Sunday.

Toru Kubota, a Tokyo-based documentary filmmaker, was arrested on Saturday by plainclothes police after a flash protest in Yangon, according to Typ Fone, a leader of the group Yangon Democratic Youth Strike, which organized the rally. Like many activists, he uses a pseudonym for protection against the military authorities.

Myanmar's army seized power in February last year by ousting the elected government of Aung San Suu Kyi, and has since cracked down hard on dissent.

According to a detailed tally compiled by Myanmar's Assistance Association for Political Prisoners, at least 2,138 civilians have been killed by the security forces and 14,917 arrested since the military takeover.

Last week, the military government drew sharp international criticism after announcing that it had hanged four activists convicted of terrorism in secret trials.

Typ Fone told The Associated Press that two protesters in Saturday's march were also arrested and detained in a township police station. The arrests were also reported by several other anti-government groups.

An official from the Japanese Embassy told The Associated Press that a Japanese national was reported detained, but declined to reveal details. The man is being held for questioning at a police station in Yangon and the embassy was taking action to release him, said the official, who asked not to be identified because was not authorized to share information with the media.

The government hasn't announced Kubota's arrest, and state-run daily newspapers, which usually report on arrests of pro-democracy protesters, did not mention it either.

However, pro-military accounts on the Telegram messaging app said the Japanese was arrested not for taking pictures but for participating in the protest by holding a banner. Typ Fone said that photos of Kubota with the banner uploaded to the Telegram channels were taken after he had been arrested, indicating they were done under duress.

During the march, about a dozen protesters chanted slogans opposing the military takeover, and shortly after, scattered into the crowds in the surrounding streets.

"He was taking a picture with his camera from a short distance from our strike yesterday," Typ Fone said of Kubota. "When we finished the strike and dispersed, he was arrested by the security forces in plainclothes and put into a Probox car." The vehicle is typically used by taxis in Yangon, and Typ Fone said the car in question also had the markings of a taxi.

According to a portfolio of Kubota's work online, his primary focus was on ethnic conflicts, immigrants and refugee issues, and he has tried to highlight the conditions of "marginalised, deprived communities."

It says he has worked with media companies such as Yahoo! News Japan, VICE JAPAN and Al Jazeera English.

Virtually all independent journalism in Myanmar is carried out underground or from exile.

The military government has arrested about 140 journalists, about 55 of whom remain detained awaiting charges or trial. Kubota is the fifth foreign journalist to be detained, after U.S. citizens Nathan Maung and Danny Fenster, who worked for local publications, and freelancers Robert Bociaga of Poland and Yuki Kitazumi of Japan, all of whom were eventually expelled.

Most of those still detained are being held under the charge of causing fear, spreading false news, or agitating against a government employee. The charges carry up to three years in prison.

From The Associated Press