Tokyo police arrested two individuals Saturday during a protest march for allegedly assaulting riot officers, authorities said.

The pair — an unidentified man and woman — were taken into custody on suspicion of obstructing official duties, according to the Metropolitan Police Department.

Both suspects have remained silent during questioning, but investigators believe they are affiliated with the Revolutionary Communist League, a far-left group known in Japan as Chukaku-ha.

The alleged incident occurred Saturday afternoon near the Toranomon area in Tokyo’s Minato Ward, where a protest march against constitutional revision and other causes was organized. The two suspects are accused of punching two riot officers in the face as police attempted to manage the demonstration.

Roughly 600 people joined the march, which called for the abolition of the U.S.-Japan security alliance, police said. Authorities believe the organizing committee for the protest was effectively led by Chukaku-ha.

Translated by The Japan Times