BERLIN (Reuters) - German police have arrested a Syrian man in Berlin on suspicion of being a member of a foreign terrorist organization, local police tweeted.

The man, who officers said had given his age as 27, had been living in Germany since 2015, police said.

He was arrested in an apartment in the Schoeneberg district and an investigation has begun.

German security services, fearing Islamist attacks, are on high alert. In October, a Syrian refugee was arrested on suspicion of planning a major attack in Berlin after police discovered explosives in his apartment.

Almost 900,000 migrants arrived in Germany last year and while many Germans initially welcomed them, security concerns have since increased, especially after migrants carried out several violent attacks on civilians over the summer, two of which were claimed by Islamic State.

There have also been attacks on asylum seekers and their accommodation facilities. On Tuesday suspected far-right extremists threatened asylum seekers in the town of Bautzen.