German state interior minister Ralf Jaeger has said migrants were almost exclusively responsible for the attacks on women in Cologne on New Year's Eve.
More than 100 women reported being threatened, robbed or molested during the city's celebrations.
The minister's comments come amid reports a group of Pakistanis and a Syrian were violently attacked by about 20 unknown assailants on Sunday in the city.
The chief of police in Cologne has been "relieved of his duties" after a series of violent attacks and sexual assaults in the city on New Year's Eve, Reuters reports, citing a state government source.
Wolfgang Albers, aged 60, faced heavy criticism over his handling of the attacks, in which around 1,000 "foreign-looking" men mugged, threatened and assaulted women in the city centre as they rang in 2016.
He has reportedly now been told by state interior minister Ralf Jaeger that he would be given early retirement.
An official announcement is expected later today.
The German Chancellor wants increased powers to block foreigners from being granted asylum if they have any sort of criminal record.
Around 400 people gathered in Cologne to demonstrate against violence against women following a wave of assaults on New Year's Eve.
Authorities in Cologne are holding crisis talks on Tuesday after a string of sexual assaults by large gangs of men.