Cologne is on high alert ahead of its giant carnival festivities since a shocking spate of sexual assaults, with German authorities anxious to prevent a repeat of the rampage and ward off potential jihadist attacks, AFP reports.

The carnival festivities kick off on Thursday with street parties - a week-long binge of beer, song and dance by revelers in fancy dress - and run through Ash Wednesday on February 10.

In the run-up to carnival, German authorities are determined to put on a good show. Some 2,500 police officers have been called in to patrol the streets, three times as many as last year, as the security budget reached 360,000 euros.