German prosecutors are investigating Mark Zuckerberg and other Facebook executives, a spokesman for the Munich prosecutor's office said on Friday, following a complaint alleging the company broke national laws against hate speech and sedition by failing to remove racist postings.

The spokesman declined to provide further details. German attorney Chan-jo Jun had filed a complaint with prosecutors in the Bavarian city in September and demanded that Facebook executives be compelled to comply with anti-hate speech laws by deleting racist or violent postings from its site.

Facebook's rules forbid bullying, harassment and threatening language, but critics say it does not do enough to enforce them and has failed to staunch a tide of racist and threatening posts on the social network during an influx of migrants into Europe.

Prosecutors in Hamburg earlier this year rejected a similar complaint by Jun on the grounds that the regional court lacked jurisdiction because Facebook's European operations are based in Ireland.

"There is a different view in Bavaria," his firm Jun Lawyers of Wuerzburg in Bavaria said in a statement.

"Upon Jun's request, Bavarian Justice Minister Winfried Bausback said that Hamburg's view was wrong and German law does indeed apply to some of the offences," it said.

Jun's complaint named Facebook founder and chief executive Zuckerberg and nine other managers at the company, including Chief Operating Officer Sheryl Sandberg.

Facebook said it had not violated German law and was working on fighting hate speech online.

"We are not commenting on the status of a possible investigation but we can say that the allegations lack merit and there has been no violation of German law by Facebook or its employees," a company spokesman said.

Jun has compiled a list of 438 postings that were flagged as inappropriate but not deleted over the past year. They include what some might consider merely angry political rants but also clear examples of racist hate speech and calls to violence laced with references to Nazi-era genocide.

Following a public outcry and pressure from German politicians, Facebook this year hired Arvato, a business services unit of Bertelsmann, to monitor and delete racist posts.

A rash of online abuse and violent attacks against newcomers to Germany accompanied the influx of hundreds of thousands of migrants last year, which led to a rise in the popularity of the anti-immigrant Alternative for Germany (AfD) party and has put pressure on Chancellor Angela Merkel.