BERLIN, Jan. 9 (Xinhua) -- German police have broken up demonstrations of the anti-immigrant Pegida supporters and right-wing extremists after they clashed with police on Saturday in the western German city of Cologne.

Right-wing extremists and Pegida supporters attacked police with bottles and firecrackers during a demonstration in Cologne, German media Focus Online reported.

The police then reacted with water cannons and broke up the demonstration of about 1,700 people.

According to the police, three officers were injured in the clashes. About half of the approximately 1,700 demonstrators are hooligans.

The demonstrations were reportedly sparked by the sexual assaults on New Year's Eve in Cologne.

A group of about 1,000 men surrounded, harassed and robbed, especially women in the city.

According to eyewitnesses and victims, the perpetrators were men of Arab and North African appearance.

The number of criminal charges after the assaults has increased dramatically from around 170 to 379, German police said on Saturday.

So far, German police have identified a total of 31 suspects, most of whom were asylum seekers.

German Chancellor Angela Merkel has announced her party has decided to take tougher action against criminal refugees.