Satellite tracking indicates New Zealander Madonna Harris is leading the 1000-kilometre Mongol Derby.

The race on the Mongolian steppe got under way on August 7.

The 16 competitors must complete the race within 10 days, changing their native horses at specially set-up stations at intervals of no more than 40km.

Its promoters say the derby celebrates the horseback messenger system used by the warrior Genghis Khan.