German police have asked prosecutors to investigate a far-right lawmaker for possible incitement to hatred, after she criticised a police force for tweeting in Arabic “to appease the barbaric, Muslim, rapist hordes of men”.

Police in the state of North Rhine-Westphalia (NRW) posted a New Year’s Eve greeting in Arabic as well as German, English and French.

Cologne, a city where groups of mainly Arab immigrants were accused of sexual assaults at New Year’s Eve celebrations two years ago, is located in the state.

“What the hell is wrong with this country? Why is the official page of police in NRW tweeting in Arabic,” Beatrix von Storch, a member of the anti-immigrant Alternative for Germany (AfD) party, wrote in a Dec. 31 tweet that was later deleted by Twitter after receiving complaints from members of the public.

“Are they seeking to appease the barbaric, Muslim, rapist hordes of men?” she added.

Twitter suspended her account for some 12 hours after she posted the message, saying it breached the website’s rules that bar users from posting hateful content.

Social media platforms face hefty fines in Germany if they fail to remove hateful posts swiftly, and companies like Facebook and Twitter have hired extra staff to monitor such messages.

The NRW police deployed large numbers of officers to secure New Year’s street parties in large cities this year, and said celebrations were largely peaceful.

Prosecutors in NRW must first decide whether they should deal with the police complaint against von Storch, or transfer the case to Berlin authorities where her constituency is.

If prosecutors deem there is sufficient grounds to launch an official criminal investigation against von Storch, they would first have to ask parliament to suspend her immunity before proceeding with a case.

Cologne Chief Prosecutor Ulf Willuhn said prosecutors must now decide whether von Storch’s message amounted to “inciting people to commit violence against a certain section of society”.

Twitter also deleted a message by AfD member Alice Weidel, in which she said German authorities wanted Germans to live with criminal mobs of migrants.

The AfD won seats in parliament for the first time in September, riding a wave of discontent against Chancellor Angela Merkel’s decision in 2015 to open Germany’s borders to more than a million asylum-seeking migrants.

The AfD, which says Islam is incompatible with the German constitution, is the third largest party in parliament. It has upended German politics by stealing voters from Merkel’s conservatives and the centre-left Social Democrats, making coalition building more difficult.

AfD leaders reacted angrily to Twitter’s decision to delete the two postings under a new law passed by parliament in June that authorises fines of up to €50m (£44.3m) against social media networks if they don’t promptly remove hateful content.

“The censorship law of Justice Minister Heiko Maas has already showed on the first day of the year its ability to curtail freedom of expression,” said AfD co-leader Alexander Gauland.

“I call on every social media user to take action against such oppression by reposting the deleted comments again and again!”