Thousands of runners have been told they missed out on completing a marathon by 264m after a blunder.
Organisers of last month's Marathon of the North have confirmed most entrants took the wrong route along part of the course in Sunderland due to a marshalling error.
In fact, only the eventual winner - Jake Harrison of Leicester Tri Club - took the correct route through the section of the course, which is close to Sunderland's Stadium of Light. This meant around 5,000 runners missed out on running the full length of the marathon or half-marathon courses at the event on April 28.
In a statement given to the Sunderland Echo, DS Media & Events said: "Regrettably, due to incorrect placing of marshals, which we take full responsibility for, only the lead athlete followed the correct route through the Sheepfold area near the Stadium of Light.
"Unfortunately, the second and third placed runners were not within line of sight of the leader and lead bikes/vehicle.
"This resulted in all those who followed taking an incorrect route through this section.
"Our course measurer has now confirmed that 264 metres were therefore lost from the measured route.
"We are sincerely sorry for any confusion and frustration that this has caused."
The organisers said they are offering the affected runners 25% off entry to other events and said they hoped the error would not put competitors off future participation.