The son of a man arrested in Sydney over an alleged plot to bring down an aeroplane with a bomb or deadly gases studied aviation management and mixes with a network of pilots and airline workers, it can be revealed.

The revelation comes as sources confirmed to Fairfax Media that the Sydney cell behind the alleged plot were talking to foreign fighters in Syria in communications that were picked up by allied intelligence agencies.

It is understood that British and US spies fed the information to Australia, triggering police to bring forward a planned operation by launching dramatic raids in Surry Hills, Punchbowl, Wiley Park and Lakemba on Saturday evening.

Four men – two middle-aged fathers, one adult son and a relative in his 30s – remain in custody at the Sydney Police Centre on suspicion of attempting to build an improvised explosive device that they could smuggle onto a plane, believed to be a commercial flight to Dubai.