This is the heartwarming moment a runner in Thailand stopped inches from the finishing line to turn back and carry an injured competitor.

Footage from September 8 shows a runner in a green top sacrifice his own time of just under 39 minutes to turn back and lift the injured man across the line.

The athletes had been racing in the 10K event in Bangkok, when one experienced sudden fatigue known as ''marathon bonk'' or ''hitting the wall''.

The runner in a white shirt suddenly collapsed on the track just a few strides away from the finishing line.

He was struggling to get up to finish the race by himself when another participant noticed him on the ground.

Three staff who witnessed the incident then rushed to help.

The exhausted marathon runner was later taken to the first aid room at the stadium.

Spectator Lalita Photchimphlee, 22, filmed the touching moment while she was in the crowd at the 10k Thailand Championship 2019.

She said: ''Marathon bonk is like a cramp but it feels so much worse and lasts longer than normal cramps. It can happen to any runners no matter how strong or healthy they are.

''That man didn't hesitate to help his colleague even though he knew that he was going to waste his recording time. His action is just really impressive.''