Al Jazeera journalist Ahmed Mansour says he will fearlessly report the truth about Egypt, despite a vow by Egyptian authorities to "hunt me down until I am arrested and brought back to Egypt".

The prominent journalist for Al Jazeera's Arabic channel was released on Monday after spending almost 48 hours in detention in Berlin as a German court considered a request by Egypt to extradite him.

Mansour thanked his supporters but expressed his disappointment in Germany, urging democratic countries to reject the requests of dictatorships following his arrest over Egypt's "baseless allegations".

"We are very sorry that a democratic country like Germany responded quickly to a request submitted by a military dictatorship against myself, a well-known journalist in the Arab World," Mansour said.

"My arbitrary arrest took place despite the German authorities and the world’s knowledge of the repressive measures carried out by the Egyptian military dictatorship in oppressing free media with systematic detention and torture against journalists and in particular towards Al Jazeera journalists in Egypt.

“Therefore, I call on the world and in particular the democratic countries of the world to take the necessary measures at all entry points to their ports and airports to avoid the repetition of the humiliating and embarrassing arbitrary arrests against journalists who are just doing their job of honest reporting."

Mansour was arrested at Berlin's Tegel airport on Saturday as he tried to board a Qatar Airways flight from Berlin to Doha, Qatar.

Responding to questions on Mansour's arrest, a German foreign ministry spokesman told Reuters news agency on Monday that no one would be extradited from Germany if the defendant risked facing the death penalty.

Mansour said that Egypt's attorney general said there were 180 cases against him "simply for defying the voice of dictatorship in Egypt".

"I am innocent and I was set up in a fabricated, baseless, groundless case," Mansour said.

Al Jazeera’s acting director general Mostefa Souag called Mansour's detention "an unfortunate incident." 

Al Jazeera journalists Baher Mohamed and Mohamed Fahmy are still on trial in Egypt after being released on bail. They were arrested in Cairo along with reporter Peter Greste in December, 2013.