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.
Thousands of anti-Islam protesters have marched through the streets of Leipzig, Germany.
Members of far-right group Pegida (Patriotic Europeans against the Islamisation of the West) joined a demonstration by their Leipzig sister movement Legida.
Holding banners and shouting slogans including "Merkel needs to go", the event was organised in protest over the mass violent and sexual assaults which took place in Cologne on New Year's Eve.
The attackers have been widely described as looking of "Arabic" and "north African" descent.
A rival anti-Pegida rally was held at the same time - and according to ITV News deputy news editor Zoe Kalus, who was in Leipzig, that outnumbered the Legida rally.
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.