Launching a national aviation green paper in Canberra yesterday, Transport Minister Anthony Albanese said the Government was searching for a second airport site near Sydney, but would not build it within the city's basin.

It was likely that long-term thinking would turn to the possibility of an international airport being developed at either Newcastle or Goulburn, linked to Sydney by rail.

Mr Albanese also boosted Canberra Airport's campaign to become a 24-hour freight hub by ruling out any need for a night curfew.

Last month, Mr Albanese rejected the airport's master plan and asked for more details.

But he supported protecting freight activities, and opposed residential developments under flight paths.

"In terms of Canberra Airport and a curfew, I don't think there is a case there for a curfew at the moment," he said.