Police in Cologne have detained hundreds of men 'seemingly of African descent' as part of operations to prevent a repeat of attacks in the German city a year ago.

Force chiefs said the men were detained at two main railway stations so officers could question them and check their identities.

Authorities deployed more than 1,500 officers across Cologne for new year celebrations in response to criticism that they failed to stop hundreds of robberies and sexual assaults last year, blamed largely on men of North African origin.

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Police in Cologne were on guard when people gathered near the city's Cathedral on New Year's Eve

Police officers stand watch in front of Cologne Cathedral, not far from where hundreds of women were sexually assaulted last year

Some revellers this year complained on Twitter that police appeared to be detaining people based on their appearance.

By early Sunday police had received reports of two women being sexually assaulted in the city. One man was arrested and three remain on the run.

The number of police on duty last night, backed by up by hundreds of volunteers and public order officials, was ten times the number last year.

Fireworks were banned in and around the station and the cathedral outside, security zones checked the bags of revellers who came to watch a light show by a Berlin artist and anyone drunk or threatening was turned away.

There were locals who said the light-hearted spirit of New Year's Eve had evaporated due to the overwhelming security presence, but in the wake of the events of 2015 - and the truck attack on a Christmas market in Berlin on December 19 - most were grateful for the police operation.

German police officers gather near the Hauptbahnhof before New Year celebrations for 2017 in Cologne, Germany

German Police stand in front of the Cathedral in Cologne, Germany, on New Year's Eve after hundreds of women were attacked in the city

A police spokesman said: 'Overall the situation dissolved quickly and quietly because many parties left the city by train.'

Cologne Police President Jürgen Mathies said: 'On the whole, the security plan worked'.

In total six people were arrested in the course of the evening.

Police had installed new video surveillance cameras to monitor the station square after women were attacked nearby last year.

The attacks in the western German city fuelled criticism of Chancellor Angela Merkel's decision to accept almost 900,000 migrants last year.

A leaked police document revealed the bulk of the crimes were committed in Cologne and Hamburg where 600 and 400 sexual assaults on women were reported respectively.

Authorities increased police presence at hotspots in the major cities, including Cologne.

Policemen walk around the main train station on December 31, 2016 during the New Year's Eve celebrations

German police officers carry barriers near the Hauptbahnhof before New Year celebrations for 2017 in Cologne

A security officer carried out a security check in front of the famous Cologne Cathedral on Saturday night