BERLIN (AFP) - Germany's intelligence service believes fighters of the Islamic State in Iraq and Syria (ISIS) in northern Iraq possess anti-aircraft weapons that could take down passenger jets, according to a newspaper report on Sunday.

The BND federal intelligence service had told German lawmakers about its suspicion in a confidential briefing late last week, reported the Bild am Sonntag newspaper without citing named sources.

In the briefing, the BND reportedly warned that ISIS fighters possess portable rocket launchers captured from Syrian army stocks. Some dated from the 1970s, while others were modern and advanced.

The shoulder-mounted rocket launchers - known as Man Portable Air Defence Systems or MANPADS - were of Russian design but may have been manufactured in other countries including Bulgaria or China, the report said.