Japan's Tokai Challenger was on Monday leading a solar car race across the harsh Australian Outback, having covered about half of the 3,000 kilometre (1,860 mile) desert course, officials said.

The Tokai University car was about 71 kilometres (44 miles) ahead of its nearest competitor, the University of Michigan's Infinium, by late afternoon as the cars sped down the Stuart Highway through Australia's heartland.

"It is thought the Tokai Team will likely camp tonight south of Alice Springs at 1,540 kilometres from Darwin," race organisers said in a statement.

The solar cars are two days into the race from the northern city of Darwin to the South Australian capital of Adelaide, which they are expected to reach by Wednesday or Thursday.

The Global Green Challenge contest involves production and prototype eco-friendly vehicles that are, or soon will be, available to the public.

The vehicles race for nine hours each day and the teams camp each night by the side of the road.

(c) 2009 AFP