A Dáil debate on the progress of the Dublin Port Tunnel is to be requested by Dublin North Central TD Mr Finian McGrath.
Mr McGrath said yesterday the construction of the tunnel was "in crisis", with "serious design flaws, leaking tunnel walls and deficient floors".
The claims were condemned by the city council, which said the tunnel has been subject to a campaign of "misinformation".
Mr McGrath said a letter from the city council's consultant engineers to the builder's project manager, Mr Chris Sedman, revealed the council's concerns about the tunnel floor in the cut-and-cover section.
The letter, seen by this newspaper, referred to the council's belief that design flaws in relation to the tunnel floor "were so great that we consider the design to be unsafe".
Speaking yesterday, the council's project manager, Mr Tim Brick, described the leaked letter as "a draft", and insisted that the "consultant engineer was doing what he was paid to do" in finding faults with the tunnel.
However, he insisted that should any changes be needed to the floor of the sections concerned "these measures would be relatively straightforward and uncomplicated to carry out. By their nature they would not contribute to delays".
Mr Brick also criticised "misinformation going about that there is any danger to the people of Marino, Whitehall or Santry, or that the council has held emergency crisis meetings about the project".
