Police use pepper spray against supporters of anti-immigration right-wing movement PEGIDA during a demonstration march, in reaction to mass assaults on women on New Year's Eve, in Cologne, Germany, Jan 9, 2016. [Photo/Agencies]

BERLIN - German police used water cannons and tear gas after protesters against New Year's Eve sex assaults threw bottles, firecrackers and stones at officers on Saturday in the western German city of Cologne.

According to the police, three officers were injured in the clashes. Local media reported that a freelancer journalist was also wounded.

About 500 of some 1,700 demonstrators were supporters of Pegida, an organization that opposes immigration from the Middle East, police said.

Fifteen people were arrested but that figure may grow as the police continue checks based on video shots.

The demonstrators are protesting against assaults on New Year's Eve in Cologne, when a group of around 1,000 men surrounded, harassed and robbed especially women.

German Federal Police detected 32 crimes on the New Year's Eve at Cologne's Central Station, with 31 suspects having been identified by names, German media Focus Online reported on Friday.

According to the report, two-thirds of those identified suspects were asylum seekers, said a spokesman from the German Interior Ministry on Friday, citing a preliminary report of the German Federal Police.

These offenses are mainly about bodily injury and thefts, he said, adding that the asylum seekers were not previously associated with sexual offenses.

German Chancellor Angela Merkel announced on Saturday that her party had decided to take tougher action against criminal refugees.

"If criminal offenses are committed and people stand outside the law ...then there must be consequences for the asylum applications and applications for residence permits," said Merkel.

The changes are "in the interest of citizens, but also in the interests of the vast majority of the refugees as well," she said.

She also said that serial offenders who repeatedly commit theft or repeatedly offend women need to "feel the hardness of the law."

The assaults in Cologne were "disgusting, criminal deeds that require robust responses," said Merkel.

Right-wing parties in the country have renewed calls for caps on the number of refugees and asked Merkel to implement tighter border controls.

The event has had major bearing on the Germans' mentality. According to a latest poll by broadcaster ARD, 30 percent of respondents said they would avoid big crowds because of the events in Cologne.

The ARD poll also showed 57 percent of those asked wanted to reinstate border controls, up 12 points from September.

Merkel won international fame last year when she announced Germany could cope with the 1.1 million migrants who arrived in 2015 amid mounting pressures.

The chancellor said she would consider a number of measures, including moves to boost police forces and efforts to sharpen the country's deportation system.

However, she also called for continued discussions on "cultural coexistence".

"We have a duty to give the right answers," she said.

Following revelations of the Cologne assaults over New Year's Eve, similar events were also reported in other parts of Europe including Austria and Switzerland.

Analysts said those events may fuel outcries against refugees in Europe,making it even harder for bolder leaders to continue embracing for incoming refugees.