The Heath & Safety Authority has said it will not compromise on the issue of removing asbestos from Ballymun's 36 tower blocks.
The HSA says asbestos-containing material must be removed before the flats are demolished.
The authority rejected suggestions that its stance was delaying the €2.5bn project.
There are 120 tonnes of asbestos in Ballymun contained in a sealant used on walls and ceilings in the flats.
The Authority's chief executive, Tom Deegan, said asbestos causes cancer in humans. The HSA’s position was based on law and science, Mr Deegan said, and there would be no compromise.
Ballymun Regeneration Ltd, the company that was set up to redevelop the area, says the amount of asbestos involved is very small.
The firm added that removing the asbestos would delay the project by up to four years and cost up to €120m.
