Cr Bob Cook has tabled a submission to the council's Laman Street Trees Working Party that proposes removing the trees and planting new ones once underground cables have been removed.

He says proposed monitoring of the trees using an "accelerometer" to establish whether they are safe could cost the council $100,000.

"We must face the reality that though we treasure the ambience of the existing trees, they have not always been this way, and new trees can be this way again if not done properly," Cr Cook said in his submission.

"Evidence indicates the current trees cannot be safely retained or replaced under the current circumstances."

Cr Cook said the working party had received new information since the council resolved in December last year to keep the trees.

That information included an estimate that monitoring the trees with an accelerometer over six to 15 months would cost up to $100,000.

Cr Cook said a staged removal and replacement of the trees, favoured by many councillors, was not possible.

Underground cables would need to be removed to establish a new "root vault", and this could not be done while trees remained in place, he said.

The proposal has angered members of the Save Our Figs group, which campaigned strongly to retain the trees and helped fight a NSW Land and Environment Court battle with the council last year.

Group spokeswoman Caity Raschke said she had expected the issue to reignite.

"The trees never actually felt saved for me," Dr Raschke said.

She said Cr Cook's proposal was "astounding" given the council's December decision to keep the trees.