Perth-based New Zealander Dave Murray has unofficially finished 16th after 10 days in the world's longest and toughest charity horse race across Mongolia.

Murray, formerly of Tekapo, New Zealand, was one of 25 riders from nine countries to race more than 1000km across the Mongolian plains from August 22, in the inaugural Mongol Derby. The challenge was officially recognised as the world's longest, toughest horse race by the Guinness Book of Records.

As the sun set over the 10th day of the inaugural Mongol Derby, Murray was unofficially 16th, according to the global positioning system. Official details of who actually crossed the lines in which order is yet to be confirmed, because of the remote location of the finish. It is understood two other New Zealanders, Hannah Ritchie and Charlotte Davison, finished strongly.

Six mobile veterinary teams, made up of teams of Mongolian, British, New Zealand and South African vets, have checked every single horse in and out of each horse station.

Murray admitted to officials of feeling 'depressed' at the thought of the finish, because he was enjoying the challenge of the race so much. This was soon after he had performed a haka, in his tights, to an assembled crowd.

He slept each night in a tiny one man tent and lightweight sleeping bag. He had to lose 14kg to get under the 85kg riding weight which included food and survival gear for the duration of the race.

Murray, 29, raised thousands of dollars to go to the Christina Nobles Children's Foundation which provide homes to Mongolian families who have become homeless. Many children live in underground sewers and huddle beside hot water pipes to stay warm in the bitter winter months, where the temperature plummets.

The first annual Derby race was framed around the communications system used by Genghis Khan, a kind of pony express using a relay system which was able to get a message from Mongolia to Eastern Europe in just 14 days. The riders have used up to 700 horses, each of them finding their own route across Mongolia.