A traditional German summertime festival descended into chaos as groups of young men, a number of whom were migrants, turned violent and committed sex attacks, according to police.

Nine sexual assaults were reported during the opening weekend (15-16 July) of the fair in Schorndorf Castle, Baden-Wuerttemberg. Meanwhile, police officers were showered with glass bottles from a mob reported to be 1,000-strong.

A 17-year-old girl was forcibly held and had her buttocks groped on Saturday. Three Afghans are being questioned in connection with the incident, according to The Local.

In another case, a 25-year-old woman reported that a man had grabbed her multiple times on her backside. A 20-year-old Iraqi refugee was questioned but police subsequently let him go without charge.

A total of 53 crimes were recorded by police during the festival. No officers were injured although six police cars were damaged.

"The violence faced by police was shocking," a police spokesperson said, adding that the level of aggression seen at the festival was unprecedented.

Police were clear that some German youths were involved in the disorder but that a large portion of the group were from "migrant backgrounds".

"Schorndorf is a symbol of what is happening on a daily basis in many places in Germany," said Jens Spahn, a member of Chancellor Angela Merkel's conservative CDU party.

"It is becoming ever more clear how big the task of integration is. Too many people are of the opinion that every other culture is an enrichment. I do not feel that the everyday debasement that women experience is an enrichment," he added.

Schorndorf is a traditional German town in Baden-Wuerttemberg. Wikicommons

Spahn was quickly rebuked for his comments by Ralf Stegner of the centre-left SPD, who said the far-right AfD party's praise for his comments rendered "no further comment necessary".

Despite the disruption, authorities have been keen to stress that only a hardcore of around 100 of the youths exhibited a "high potential for violence".

"This is not a second Cologne," mayor Matthias Klopfer said in reference to spree of sexual assaults and violence during New Year's Eve 2015.