New details have emerged over the difficult lease negotiations between the site's trust and Greyhound Racing NSW, which had been seeking to remain at the prime inner-city location for another 40 years.

Wentworth Park Sporting Complex Trust board member Robert McKeown said he was ''gobsmacked'' by a proposal involving Greyhound Racing NSW, revealed by Fairfax Media at the weekend, to sell the dog track and build a billion-dollar residential complex. The site is on Crown land.

Panthers Leagues Club and developer Brookfield Multiplex are also linked to the plan, which would fund a sports stadium in western Sydney and a greyhound and harness racing facility at Eastern Creek.

''It's ludicrous. It just came out of left field and I can't for the life of me see how it could possibly happen,'' said Mr McKeown, a retired solicitor who has lived in Glebe for 40 years. ''The idea of alienating public open space … for private residential and commercial purposes is just ridiculous.''

The site is also used by schools, universities, sporting groups and community events.

The greyhound racing lease at Wentworth Park expires in 2027 and Greyhound Racing NSW has been negotiating a new lease to run until at least 2054. But it has also been exploring the prospect of moving to Eastern Creek.

Greyhound Racing NSW chief executive Brent Hogan said the industry had a legal right to operate from Wentworth Park and "if we were to be moved, we'd have to be in line for some significant compensation, including a new site".

He said lease negotiations with the trust had been "hard … in terms of reaching an arrangement which is sustainable for the racing industry".

''In that context, it is not only sensible but predictable that bodies like us would be looking at … the alternatives if we can't reach an arrangement at Wentworth Park,'' Mr Hogan said.

The trust's chairman, Percy Allan, said after more than six months of talks, the parties were yet to agree on how much Greyhound Racing NSW would pay in rent and upkeep. About $6 million in major works is required on the facility.

''We need a … minimum income in order to survive as a trust,'' he said. ''[Greyhound racing] generates a lot of income there, they maintain the facility.''

Mr Allan claimed the chances of residential apartments being built at the site was ''zilch … there would be massive community outrage''.

The City of Sydney controls the land around the racetrack. Lord mayor Clover Moore said the council had not been consulted on the plan, which is expected to be submitted to the government as an unsolicited proposal within weeks.

A spokesman for Deputy Premier Andrew Stoner, the minister responsible for Crown lands, said the government has ''no plans'' to sell the Wentworth Park site.