Turkish President Recep Tayyip Erdogan is seeking a preliminary injunction against the CEO of German publisher Axel Springer that would stop him repeating a derogatory term about the Turkish leader, Erodogan's lawyer said on Tuesday.

Ralf Hoecker, the lawyer, told Reuters Erdogan wanted the injunction due to chief executive Mathias Doepfner's support for a poem read out by comedian Jan Boehmermann on German national television in March.

In the poem Boehmermann suggested Erdogan hits girls, watches child pornography and engages in bestiality.

Hoecker said if the regional court in Cologne agreed to grant the injunction, Doepfner would no longer be able to repeat a sexually crude term to describe Erdogan that was first used by Boehmermann and subsequently quoted by the Axel Springer chief.

Hoecker added that he was seeking a preliminary injunction on Erdogan's behalf because of the urgency of the matter. A spokeswoman for the court in Cologne said she could not yet comment on the case.

The Turkish leader demanded Germany press charges against Boehmermann and Chancellor Angela Merkel has drawn heavy criticism for allowing German prosecutors to pursue a case against the comedian. Under Germany's criminal code, insults against foreign leaders are not allowed but the government can decide whether to authorize prosecutors to go ahead.

In an open letter published in German newspaper Welt am Sonntag in April, Doepfner expressed solidarity with Boehmermann, saying he had laughed out loud over the poem and "wholeheartedly" supported what the comedian had said.

Hoecker said he would recommend that Erdogan pursue his case with a higher German court if the preliminary injunction was rejected, as expected. He said he expected a quick decision.

A spokeswoman for Springer said, "We do not yet have any information about this at all. It's important to note that Mr Doepfner wanted to defend the freedom of art and satire in his open letter - that was the reason for his letter."

Hoecker's law firm published a statement on its website on Monday saying it had succeeded in getting a preliminary injunction against German director and producer Uwe Boll, who in a video posted online, defended Boehmermann's poem and said Erdogan should be shot.

"Mr Erdogan is a human being and human dignity is inviolable," Hoecker said in that statement, adding that this was placed above the freedom of press, art and opinion in the German constitution.