German police arrest Syrian bomb plot suspect Jaber Albakr

German police on Monday arrested a Syrian man suspected of plotting a jihadist bomb attack, after a massive manhunt lasting almost two days.

Security had been stepped up at airports and train stations after Jaber Albakr, 22, went on the run Saturday, when police raided his apartment and found several hundred grams of "an explosive substance more dangerous than TNT".

"We've succeeded, really overjoyed: the terror suspect Albakr was arrested overnight in Leipzig," police said on Twitter on Monday.

Police had said that "even a small quantity" of the explosives uncovered "could have caused enormous damage".

Local media reported that the material was TATP, the homemade explosive that was used by jihadists in the Paris and Brussels attacks.

Albakr was believed to have had internet contact with the Islamic State group, Sueddeutsche Zeitung reported.

According to security sources quoted, he had built "a virtual bomb-making lab" in the flat in a communist-era housing block and was thought to have planned an attack against either one of Berlin's two airports or a transport hub in his home state of Saxony.

Acting on a tip-off from the domestic intelligence agency, police commandos had sought to swoop on the Syrian early Saturday at his apartment building in the eastern city of Chemnitz, about 85 kilometres from Leipzig.

But he narrowly evaded police, local media said.

He was finally caught in the early hours of Monday after police learnt that he had sought help from two Syrians in Leipzig, Spiegel Online reported.

Meanwhile, Albakr's Syrian flatmate has been formally remanded in custody as a suspected co-conspirator of a "serious act of violence" while two other of his associates, who had been detained earlier, have been released.

Police commandos on Sunday also raided the Chemnitz home of another suspected contact of Albakr, blasting open the door as they stormed the premises, and took away a man for questioning.

Spiegel said Albakr had entered Germany on February 18, 2015 and two weeks later filed a request for asylum, which was granted in June that year.

Germany has been on edge since two IS-claimed attacks in July -- an axe rampage on a train in Wuerzburg that injured five, and a suicide bombing in Ansbach in which 15 people were hurt.