A mother survived on breast milk after she got lost during a race in a New Zealand forest.

Susan O'Brien, 29, disappeared without trace while competing in the XTERRA Wellington Trail Running Series at Rimutaka Forest Park on 10 May, prompting a mass search and rescue of the area.

The mother-of-two resorted to drinking her own breast milk to survive and buried herself in the dirt to keep herself warm overnight.

She was eventually found 24 hours later when a helicopter spotted her using heat-detecting technology.

Police said she took a wrong turn and got lost after trying to make her way back to the trail.

She was reunited in an emotional reunion with her husband Daniel O'Brien and her brother, Jack Khoo, as well as her eight-month-old and two-year-old.

Race organiser Mike Thomason said 423 runners took part in the 20km race at around 9am. O'Brien was expected to finish by 11.30am but by midday the alarm was quickly raised that she had not returned.