Sutherland Shire Council has signalled it will fight any attempt to turn Miranda Park into "a bitumen corridor" for the F6 motorway extension.
The expansive open space next to Port Hacking High School, which is used for circuses, amusement fairs, schools' cross country running, dog walking and other recreation, has been part of the F6 motorway reservation since 1951.
The council, at its meeting on Monday night, amended a draft long-term transport strategy for the shire to spell out the importance of existing open space along the route.
The strategy calls for further stages of the F6 extension, along with a proposed mass transit system between Kogarah and Miranda, to be expedited.
The council wrote into the document this should be subject to the optimum retention of open space within the corridor, which should also provide "multi-modal transport options".
Cr Kent Johns, an influential figure in the NSW Liberal Party, emphasised the importance of preserving Miranda Park.
"I want to make it clear [in the strategy] that area should be in a tunnel or cut and covered so there is no ambiguity at all," he said.
"If that is to become a bitumen corridor, it is not acceptable to residents of B Ward."
Council staff were asked to quantify the open space that would be affected by an extension of the motorway.
That information will be considered by the council before the strategy is finalised after public consultation.
Cr Barry Collier, who as the MP for Miranda, opposed the F6, said the future of community land from Gymea to near Kirrawee High School was another big issue.
Last year, Miranda MP Eleni Petinos told State Parliament Miranda Park needed to be retained as a recreation area for thousands of new apartment dwellers nearby.
Cronulla MP and Attorney-General Mark Speakman told Parliament he "endorsed" Ms Petinos's comments, but he was more cautious later when he told the Leader his "strong preference" was the park should be retained.