Myanmar's military rulers have acknowledged that they have Japanese journalist Kubota Toru in custody. But they have offered no prospects for his release.

The Japanese Embassy in Yangon said a Japanese man in his 20s was detained by security forces last Saturday when he was covering a protest against the ruling junta.

A spokesperson for the military's governing council, Zaw Min Tun, on Tuesday revealed to NHK that the detained man is Kubota. Zaw Min Tun said Kubota had been talking with demonstrators and is currently under investigation. But he made no mention of his release.

Kubota is believed to be in a police building in Yangon.

Japanese embassy officials are asking to meet Kubota in person, but so far they have not received permission.

The officials say they will keep trying to secure his early release through diplomatic channels.