The giant fig tree sits astride a double block of land comprising numbers 6 and 8 Grand View Parade, Lake Heights, which was set to go to auction at 9.30am.

But after residents expressed concern about the loss of the tree - prompting questions from the Mercury - the NSW Land and Housing Corporation late on Friday "postponed" the auction.

It had become clear the tree was protected, with Wollongong Lord Mayor Gordon Bradbery telling the Mercury the ficus is on the heritage register.

"No way," he said.

"That's a heritage listed fig tree. I've made it very clear that whoever buys it is buying the encumbrances that are there.

"It's the only tree I know of in that area that has a heritage listing on it.

"I would advise anyone who's going to take it on to do their due diligence.

"It's protected under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 - also the NSW Biodiversity Conservation Act 2016 as habitat for the Grey Throated Flying Fox and possible Aboriginal cultural values."

At 5.50pm on Friday, the Land and Housing Corporation, part of the the Department of Planning, Industry and Environment, said the auction was off.

"The auction has been postponed," a spokeswoman said. "The department is consulting with various stakeholders regarding future options for the site."

It is unclear how the sale had proceeded so far given the heritage listing.

Contacted earlier in the day, selling agent Lou Niceski of Elders Wollongong would not comment on the outlook for the big old fig.

"It's not anything," he said.

"It's not my land. Go away"

Lake Heights resident John Gnomes sounded the alarm about the tree's future in a letter to the Mercury last month.

He said the block was large enough to build on without having to cut down the "ancient and magnificent" tree.

"There is no offset possible that would replace this tree," he said.

The tree is the only thing in Lake Heights included on the environmental heritage register of the Wollongong Local Environment Plan 2009.

Trees on the Wollongong heritage list include Norfolk Pines at beaches, Spotted gums and Hoop pines in Mangerton, Canary Island pines in North Wollongong, Bunya Pines in Dapto - and several figs, including Moreton Bay figs, Hills figs, Small leafed figs - in many suburbs.

The tree is the only object in Lake Heights included on the environmental heritage register of the Wollongong Local Environment Plan 2009.

There are several trees on the heritage list, Norfolk Pines at beaches, Spotted gums and Hoop pines in Mangerton, Canary Island pines in North Wollongong and Bunya Pines in Dapto.

There are fig trees - including Moreton Bay figs, Hills figs, Small leafed figs - on the heritage list in many suburbs across Wollongong.