A man has been disqualified after jumping out of the crowd and running only the last one kilometre to finish second at Kenya’s Nairobi International Marathon.

Race officials said the man, identified as 28-year-old Julius Njogu, hid among a group of spectators before joining Sunday’s race near the finish.

Njogu claimed second place in a sprint finish after breezing past another competitor in the final stretch at Nyayo National Stadium. He was in line to claim around $US7,000 ($A9,500) in prize money before being caught out and disqualified.

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Officials said they became suspicious because Njogu showed no signs of fatigue and was not sweating when he had supposedly just run 42km. They discovered that he’d run barely one kilometre after emerging from a bunch of onlookers and joining the leading group of runners just outside the stadium.

Through the final few metres, Njogu jogged easily past a weary-looking Shadrack Kiptoo to cross second. Joshua Kipkorir won the men’s race in two hours, 13 minutes and 25 seconds. Elizabeth Rumokoi won the women’s title in 2:29.32.

Television images showed Njogu arguing with race officials, and even removing his running shoes in an apparent attempt to show organisers blisters on his feet to prove he’d run the entire course.

“I followed the leading team from start to finish and I didn’t see him,” said race director Ibrahim Hussein, a former Boston and New York Marathon champion.

“He will not be recognised and I’m so disappointed that one can cheat in this modern age. He didn’t finish second.”

In 2013, two athletes were disqualified at the Nairobi marathon after also attempting to cheat their way to podium finishes in the women’s race.