Hong Kong police on Thursday charged seven officers with assaulting an activist whose videotaped beating stirred outrage among city residents at the height of pro-democracy protests last year.

The seven officers were charged jointly with one count of grievous bodily harm and one was also charged with common assault, a statement from police said. They are due to appear in a magistrate's court Monday.

The activist, Ken Tsang, was among a group of protesters in a pre-dawn clash with police over Beijing's plans to restrict elections when he was videotaped being beaten in a dark corner.

Tsang was also charged Thursday with one count of assaulting an officer and four counts of resisting police, the Department of Justice said. The charges relate to moments before the incident, when officers attempted to apprehend Tsang as he splashed liquid from a bottle on police, the department said in a statement.

The accused officers, all men age 31 to 48, were working in plainclothes at the time. The charges are being laid exactly one year after the encounter that occurred during the protests that gripped the city for more than two months.

As protesters and police battled into the early hours of Oct. 15, 2014, for control of an underpass outside government headquarters, local station TVB videotaped officers taking a handcuffed Tsang behind a building in a nearby park.

The video shows the officers placing Tsang on the ground, then one punches him while several others kick him.

The officers were suspended from duty in November but Tsang's supporters accused authorities of dragging their feet after the investigation stalled.

"This is a kind of political pressure," Tsang told reporters before entering the police station on Thursday. "Very simply the purpose is to make the plaintiff become the defendant" and distract the public, he said.