1 of 3
Michael Sohn, Associated Press
A man speaks in front of a court to support the release of the journalist Ahmed Mansour in Berlin, Germany, Sunday, June 21, 2015. Mansour, 52, a senior journalist with the Qatar-based broadcaster Al-Jazeera, was detained at Tegel airport on Saturday on an Egyptian arrest warrant, Al-Jazeera said. Poster at center reads: "Stop the blood flow in Egypt".

BERLIN — A prominent Al-Jazeera journalist will remain in German custody for a second night, prosecutors said Sunday, saying they have not yet decided whether to extradite him to Egypt or set him free.

As dozens of supporters protested Sunday in front of the Berlin court building where Ahmed Mansour was being held, his lawyer, Fazli Altin, called for the journalist's immediate release, saying that Germany was getting involved in a politically tainted case.

Mansour, 52, a well-known journalist with the Qatar-based broadcaster's Arabic service, was detained at Berlin's Tegel airport on Saturday on an Egyptian arrest warrant, his lawyers said. Mansour, who holds dual Egyptian-British nationality, was trying to board a Qatar Airways flight to Doha, the station reported.

A spokesman for the Berlin prosecutor's office said Sunday that Mansour would be taken to a prison in the city and that further decisions on his future will be made next week.

Altin said a court on Monday would most likely check out the lawfulness of his possible extradition to Egypt.

Mansour's detention is the latest in a long series of legal entanglements between Egypt and satellite news channels. The station said he had been sentenced in absentia in Egypt to 15 years in prison over allegedly torturing an unnamed lawyer in Tahrir Square in 2011, a charge both he and the channel rejected.

Mansour's arrest is the result of "Egypt's terrible revenge against journalists that cross the regime," press freedom watchdog Reporters Without Borders said in a statement Sunday, adding if Germany did extradite him "it will be putting itself at service of a dictatorial regime and will dishonor itself."

Altin said Mansour was accused in the warrant "of having harmed the reputation of Egypt massively" and of having committed torture.

"It's unacceptable for the freedom of press and embarrassing for Germany that Mansour is being held here on these clearly political allegations," he said.

Patrick Teubner, a second lawyer for Mansour, said the journalist had been traveling on his British passport when he was detained. The U.K. confirmed that it was providing consular assistance to him.

"This case has clearly taken on a political dimension and there are currently lots of background talks and various consulates are also involved," Teubner said.

Both of the journalist's lawyers expressed surprise that Mansour had been detained at all. They said they thought Interpol had put out a note on Mansour, which would show up at passport controls, but that Interpol had not officially asked for the arrest of Mansour.

"According to our knowledge, Interpol refused to initiate an international arrest warrant on Mansour, so it's not really clear why he was detained at all," said Altin.

The German prosecutor's office could not immediately be reached Sunday for clarification on the issue and the German border patrol refused to say on what allegations Mansour had been detained.

Egyptian Foreign Ministry spokesman Badr Abdelattie told the AP, however, that Germany arrested Mansour based on the red flag put for him by the Interpol. He said Egyptian judicial authorities, including the chief prosecutor in Cairo, were speaking with German authorities to clarify what crimes he is wanted for.

A spokesman for the Berlin court, Martin Steltner, said Mansour would be taken from the court to a prison in Berlin's Moabit neighborhood later Sunday.

"(He) has not been set free," Steltner told The Associated Press. "Today's meeting was about formalities, next week there will be an assessment regarding the validity of the warrant."

A government judicial official told the AP next week there would be a decision on whether Mansour has to remain in custody. In addition, the Berlin Court of Justice would decide — once it gets a request for extradition from Egypt — whether Mansour can be extradited or whether the case is politically motivated.

Even if the court rules in favor of an extradition, the German government can still veto that.

A post on Mansour's Facebook page called for a "Freedom for Mansour Ahmed" protest outside the Berlin courthouse. A video of Mansour was also posted to Facebook after he was questioned in which he lashes out at German authorities for detaining him.

"Regrettably, they told me that the request to arrest me is a German request and it is not based on Interpol," he said, accusing Germany of being complicit with President Abdel-Fattah el-Sissi's government in Egypt.

It wasn't immediately clear who was posting to Mansour's Facebook account, or who made the video.

Mansour, who is known for his "Without Borders" program, recently conducted an interview with the head of the Nusra Front, the al-Qaida branch fighting in Syria's civil war, which aired last month from an undisclosed location in Syria. German media reported that Mansour was in Germany for an interview he conducted here for his show.

About 80 protesters gathered outside the Berlin courthouse Sunday, holding up his picture and shouting "Free Mansour!"

"We don't understand why Mansour was detained in Berlin," said Ali Alawady, a member of the German-Egyptian Union for Democracy who helped organize the protest. "He is an innocent journalist who is unrightfully persecuted in Egypt."

Sarah El Deeb in Cairo and Greg Keller in Paris contributed to this report.