A Syrian man suspected of planning a bomb attack in Germany on behalf of Isis (Islamic State) was arrested after being captured by fellow Syrians who tied him up and held him in their apartment before handing him over to police.
The 22-year-old refugee was preparing a suicide bomb vest which was "close to completion", according to prosecutors.
Jaber al-Bakr was arrested on Monday following a two-day manhunt.
Several hundred grams of TATP, the same powerful explosive used in the Paris and Brussels attacks, were found in his apartment.
"The methods and behaviour of the suspect suggest an Isis context," Jorg Michaelis, the police chief in the German state of Saxony, told a press conference.
"He is accused of planning and preparing an Islamist attack in Germany," prosecutors said.
Officials have not commented on the suspected target of the attack, but German media have reported it is thought to have been one of Berlin's two airports, or a transport hub in Saxony.