Planning permission for the MetroLink could be at risk.
It's over submissions by State agencies which have been described as unhelpful.
The long awaited MetroLink, which will connect Dublin airport with the city, is at the heart of the Government's transport plans.
It's awaiting planning permission and submissions to an Bord Pleanala could threaten this.
According to freedom of information requests from the Daily Mail, the DAA, the Office of Public Works and the National Parks and Wildlife Service are among those raising concerns.
Issues flagged include the design of MetroLInk and the location of some of the stops - like the one at Stephen's Green.
A senior transport official has described the submissions as unhelpful leading to concerns construction on MetroLink could be delayed.
