Exactly 15 months after New Year's Eve celebrations near Cologne's main station turned into a night of sexual assault and robbery, the state parliament in North Rhine-Westphalia (NRW) on Friday released its final report on an investigation into the incident.

Police and the Cologne city administration could have largely prevented the attacks, had they been better prepared and acted quicker, the investigatory commission concluded. According to the report, "police or other security forces intervening as quickly and especially as early as possible would have been necessary."

According to the local broadcaster WDR, the report stated:

Not enough police officer were on the ground at Cologne main train station and at the plaza in front of Cologne Cathedral where the attacks took place. Police also failed to request adequate backup when the situation escalated.

When several groups of inebriated men started acting aggressively, police initially remained inactive. This response created the impression among the perpetrators that they could get away with anything.

Police squads did not communicate well with each other. They failed to use police radios instead of cell phones even though cell service collapsed at several points during the night due to overload.

In spite of crowd control by police, a bridge near the scene of the attacks was overcrowded on New Year's Eve 2015. Some people on the bridge panicked and jumped onto train tracks leading to the main station. This resulted in overcrowding at the main station as travel was halted, which further escalated the situation.

The report alleges that police officers in Cologne did not act swiftly enough and did not coordinate their actions well enough on New Year's Eve 2015 (pictured: police in Cologne on New Year's Eve 2016)

Left out: NRW cabinet's role

The NRW parliament in Düsseldorf is expected to debate the report on Wednesday.

The parliamentary commission has been investigating the Cologne attacks since January 2016. The final report, which was over 1,000 pages, was based on testimony from roughly 180 eye-witnesses, including both civilians and police officers, as well as federal Interior Minister Thomas de Maiziere, NRW Premier Hannelore Kraft, NRW Interior Minister Ralf Jäger and Cologne Mayor Henriette Reker.

Unlike earlier drafts, the final report does not address whether mistakes were made by the NRW state administration or Chancellor Angela Merkel's federal cabinet.

Whether police failed to adequately brief Jäger had been hotly debated in Germany. The state interior minister insisted he did not know about the magnitude of the attacks when media first reported them in early January. The opposition claimed his department initially attempted to downplay or even cover up what happened in Cologne.

Opposition politicians in NRW have accused interior minister Ralf Jäger (pictured) of initially downplaying the New Year's Eve incident

This issue is particularly potent given that the state election in NRW is only two weeks away.

A coalition of center-left Social Democrats (SPD) and the Greens has been in charge of Germany's most poplous state since 2010. Conservative Christian Democrats (CDU), the free-market liberal FDP and the Pirate Party currently form the opposition in the state parliament, though the Pirates are expected to be voted out of parliament on March 14, while the far-right AfD party will likely surpass the 5 percent threshold necessary to enter parliament.

Ina Schnarrenberg, the CDU representative on the investigatory commision, said the SPD-Greens coalition had attempted to remove all criticism of Jäger and the state Interior Ministry from the report. She said the two governing parties were guilty of "deception, tricks, concealing information."

Marc Körfges, a commission member from the SPD, called the claims "absolutely untenable" and accused the opposition of "campaigning for the election at the cost of the victims."

Over 1,200 criminal charges

On December 31, 2015, an estimated 1,000 men robbed and assault individual women on a square between the Cologne Cathedral and the city's main station. Over 1,200 criminal charges were subsequently made, around 500 of which pertained to sexual assault. The incident made waves across Germany and worldwide.

Because many perpetrators were allegedly of North African or Middle Eastern descent, anti-immigration activists used the Cologne attacks to justify anti-refugee policy proposals.

On New Year's Eve 2016, the situation remained largely peaceful in Cologne, but police were criticized for "racially profiling" hundreds of men. Police officers allegedly asked predominately "Nafris" - a term which police uses to describe those who appear to be of North African descent - to present them with identification documents.