Cologne police said Friday they recorded 22 complaints of sexual assault on the first day of the city's giant carnival, after security was beefed up to prevent a repeat of the New Year's Eve crime spree that shocked Germany.

The number of cases was sharply up from the nine reported on the opening day last year, but police put it down to the greater readiness of victims to report crime.

German prosecutors said Wednesday they had received several criminal complaints against the suspended police chief of Cologne and officers for failing to prevent a spate of violence against women blamed on migrants.

"Several criminal complaints were filed against the former police chief of Cologne and other police officers in connection with the events at Cologne main rail station," said the state prosecutor for the city of Aachen.