The 27-year-old Syrian national who blew himself up in Ansbach, Bavaria had been granted humanitarian status by Bulgaria, authorities in Sofia say.

After being registered in September 2013, he filed a request for protection.

He left Bulgaria in mid-2014, according to the Interior Ministry.

The man, whose name has not been officially announced as of 22:00 Bulgarian time on Monday received two warnings about his deportation from Germany between December 2014 and July of this year. 

He also applied for protection in Germany, where his application was turned down last year, German daily Frankfurter Allgemeine Zeitung quotes Bavarian Interior Minister Joachim Herrmann as saying. 

"We have information about the case, but will not comment as of the moment," news website Dnevnik.bg quotes Georgi Kostov, the Bulgarian Interior Ministry's Chief Secretary, as saying.

Earlier, German federal authorities announced the man had been supposed to be sent back to Bulgaria.

However, Bulgarian authorities were reported as rejecting the demand for his deportation as it claimed that all the procedures under the Dublin regulation (which allows European countries to send back migrants to their first country of registration) had been met and the man was able to travel with his status.

On Monday, police found on his laptop and mobile devices Islamist videos, in one of which he pledged alliance to the Islamic State (IS) group.

Amaq news agency, said to be linked to IS, announced he had been one of its "soldiers."