The HS2 project is in a "very serious situation" and needs a "fundamental reset", the new boss of the the high-speed railway company has warned.
Mark Wild, chief executive of HS2 Ltd, said he is committed to ensuring the railway opens "safely and efficiently".
His comments come after HS2 Ltd published an update outlining the progress in building the 140-mile line between London and the West Midlands.
The government's last estimate of the overall cost for the remaining Birmingham to London stretch is between £45bn and £54bn.