Cash payments have been made to members of Indonesian people-smuggling rings by Australian intelligence officials for at least the past four years - including under the former Labor government, Fairfax Media has learnt.

Multiple sources have said that such payments have been part of successive governments' tactics, though not always as part of boat turnbacks, which were not used by the previous government.

The issue exploded into the public sphere with the claim last week - reported by Fairfax Media - that Australian officials paid $US5000 each to six crew members of an asylum-seeker boat crew to return the vessel to Indonesia.