Cologne police chief Wolfgang Albers was forced to step down today in response to criticism over his force's handling of a string of sexual assaults in the western German city on New Year's Eve.

Ralf Jaeger, the interior minister of the state of North Rhine Westphalia, where Cologne is located, said he asked Albers to leave in order to "restore the public's confidence."

Albers, head of the force since 2011, showed "great understanding" in the matter, the state minister said at a press conference.

Albers came under fire after it emerged that his officers had been short-staffed and ill-equipped to prevent the crimes, which prompted around 170 complaints mainly of a sexual nature, including two allegations of rape.

The 60-year-old did not resist Jaeger's urgings for his resignation, later saying that he "accepted" the decision in light of the major criticism that has centred around the police's management of the attacks.

"But the police officers who were on duty at Cologne Main Station on the night of New Year's Eve do not deserve this criticism," Albers said.

A chaotic scene has emerged of that night in Cologne, contradicting a police statement on January 1 stating that celebrations had passed off "peacefully," prompting allegations of a cover-up.

Around 1,000 heavily intoxicated men are thought to have surrounded, taunted and sexually assaulted women, many of whom were also robbed of their belongings.

The wave of New Year's Eve crimes in Cologne were mirrored in Hamburg, where 108 complaints were filed, and to a much lesser extent in other cities, inflaming an ongoing debate about the repercussions of allowing 1.1 million migrants to enter Germany in 2015.

Of the 32 suspects identified by police in Cologne, 22 are asylum seekers, the German Interior Ministry said.

There is evidence the asylum seekers committed offences such as theft and bodily injury of a non-sexual nature, but none are believed to have engaged in sexual assault, a ministry spokesperson said.

The suspects include nine Algerian, eight Moroccan, five Iranian, four Syrian, one Serbian, one Iraqi, one US and three German citizens.

Politicians from across the political spectrum were pushing for a security crackdown and more severe punishments for the perpetrators.

Chancellor Angela Merkel said through a spokeperson yesterday that all facts in the case would have to be known before decisions could be made about consequences for the perpetrators.

"It is important to the chancellor that the whole truth is laid out on the table and that nothing is withheld or sugarcoated," deputy spokesman Georg Streiter said, adding that hasty decisions would be detrimental to the "large majority" of innocent refugees seeking asylum in Germany.

A document to be published at the party conference of Merkel's Christian Democratic Union (CDU) on Friday proposes the introduction of random police checks across Germany in order to preempt similar crimes in the future.

- dpa

Mass sexual assault in Cologne - what we know and what we don't

Debate intensifies as asylum seekers among Cologne violence suspects

Cologne feels anxiety and anger about Merkel’s refugee policy