A lawmaker from Germany's anti-Islam, ultra-right Alternative for Germany (AfD) party was blocked on Twitter most of Monday for lashing out over New Year's greetings sent by Cologne police in Arabic.

"What the hell is happening in this country? Why does an official police site tweet in Arabic," wrote Beatrix von Storch, a leading party member for the anti-immigrant right-wing group.

She suggested the police were trying to "appease" what she described as "barbaric, gang-raping Muslim hordes of men."

In response, Twitter blocked her account for 12 hours for violating its rules regarding racist content. The tweet was no longer visible Monday, but another AfD leader, Alice Weidel, shared a screenshot of it on Facebook, lamenting the government's "submission" to migrants.

Police in the western German city of Cologne had sent out New Year's greetings in several languages on their Twitter.