Myanmar police detained a Japanese freelance journalist at a protest in the commercial capital of Yangon, a colleague said on Friday, in the first detention of a foreign reporter since the military coup on Feb. 1.

Yuki Kitazumi, who runs a media production company and used to be a journalist for the Japanese business daily, the Nikkei, according to his Facebook page and interviews with online media, was arrested on Friday morning.

"According to witnesses, he was beaten on his head but he was wearing a helmet so it didn't cause him much harm. I have contacted the embassy and haven't heard much more information yet," said Kitazumi's Myanmar colleague Linn Nyan Htun in a Facebook post announcing his arrest.

"I didn't witness it but I received a message from him via messenger app around 11:30 that he got arrested. After that I lost connection with him," he told Reuters by phone.

Japan's Chief Cabinet Secretary Katsunobu Kato told a regular news conference Japan was still trying to confirm the facts.

Myanmar police did not return calls seeking comment.

Kitazumi's phone listed on the website of his production company was unreachable.

Myanmar has been roiled by protests for weeks since the army seized power from elected leader Aung San Suu Kyi and detained her and most of her government.