With more than half a year to go until Germany - like the rest of the world - welcomes in 2017, police in the western German city of Cologne are already planning extra security measures at this year's public party.

The increased security comes in light of a series of attacks on New Year's Eve by gangs of young men outside the central railway station, in the shadow of the city's Medieval cathedral.

Investigators in Cologne received 1,170 criminal complaints of attacks - 492 of them related to assaults of a sexual nature. Eye witnesses and victims described the perpetrators as being mainly from North Africa and the Arabian peninsula; some were claimed to be Arabic speakers.

The attacks were met with shock across Germany and sparked a debate, particularly among far-right parties, over Berlin's decision to accept more than one million asylum-seekers during last year's unprecedented influx of refugees.

The commission investigating the incidents at last year's New Year's celebrations have now heard one-third of 100 scheduled testimonies.

Cordon still in question

Under the new measures at this year's celebrations, head of Cologne police Jürgen Mathies has said a "protection zone" will be implemented around the city's world-famous cathedral.

"The cathedral is an area that particularly needs protection," Mathies and city director Guido Kahlen told the "Kölner Rundschau."

"I don't want any firecrackers or rockets at the cathedral and the square in front of the train station," Mathies said.

Vacation unlikely

In an effort to deploy more officers across the city, Mathies also said it's unlikely that the city's police will be able to take a holiday during the New Year celebrations. Last year just 22 officers reported for duty.

"We will definitely be working with a clearly structured organization," Mathies said, adding that lessons learnt from previous events should "flow together."

Tighter security at Carnival

The city's security was already put to the test in February at Carnival, which attracts over a million people every year. Around 360,000 euros were invested into the extra security measures, which included an increased police presence, mobile lighting masts to illuminate dark, potentially dangerous corners, and a security point where women could report to in case of an emergency.

Authorities received reports of 22 sexual offences on "Weiberfastnacht" (Women's Carnival Day), which is celebrated on the last Thursday before Lent.

During last year's "Weiberfastnacht," only nine cases of sexual assault were reported, and 10 in the previous year. Two of the 22 offenses were deemed "serious," one of which involved a Belgian TV reporter who was groped by a reveler live on air.

'The whole world's going to be watching'

The next events come on July 3 at the Christopher Street Day parade, and on July 16, when hundreds of thousands of people are due to turn out for the "Kölner Lichter" - Cologne's annual fireworks and music festival on the Rhine.

Following the event, huge crowds are expected at the Cologne central train station as well as the nearby Deutz station. City organizers said security measures are already in place, including extensive extra lighting, not only to increase the safety of revelers, but also to provide clearer CCTV footage, in case of an incident.

The main measures for New Year should be decided upon by September. Cologne city director Kahlen said: "We know the whole world's going to be watching to see if we've learnt our lesson."