The man in his 40s was airlifted to the University Hospital of Wales on Tuesday after suffering “crush injuries” and severe blood loss.

The crush incident is understood to involve a brick grab, according to site sources.

A spokesman for Network Rail confirmed that a contractor from civil engineers BAM Nuttall Rail, which is undertaking various works at Cardiff Central, was injured in the incident.

The spokesman added: “Rest assured Network Rail will immediately be conducting a thorough investigation into this incident to find out what happened and to make sure it does not happen again, but at present our thoughts are firmly with the injured individual.”