Italian orienteering athlete Mattia Debertolis died on Tuesday at the World Games in Chengdu, China after collapsing during competition, organisers said.

Debertolis was found unconscious during an orienteering event on August 8 and died four days later, said a joint statement from World Games organisers and the International Orienteering Federation (IOF).

The World Games is a multisport event held every four years for disciplines not included in the Olympics.

"Despite receiving immediate expert medical care at one of China's leading medical institutions, he passed away," the statement said.

Orienteering sees athletes navigate an unmarked course with a map and compass, punching in at designated spots along the route in the quickest time.

The event, held about 50 kilometres (30 miles) outside of central Chengdu, took place in intense heat and humidity, with temperatures above 30 degrees.

Debertolis, from Primiero in eastern Italy, was taking part in the final of the men's middle-distance event when he collapsed.

The six-kilometre course featured 180 metres of ascent and 20 control points that athletes must visit.

Footage from the World Games' social media accounts showed athletes running through crop fields and villages on a largely rural course.

The winner, Switzerland's Riccardo Rancan, completed the course in 45 minutes and 22 seconds.

Debertolis was listed as "Did Not Finish" in official results, along with 11 other athletes.

He participated in several World Championships and World Cups as part of the Italian team.

Aside his training, Debertolis was studying for a PhD at the KTH Royal Institute of Technology in Stockholm, where he lived.