American balloonist Steve Fossett has dropped thousands of metres in a bid to dodge bad weather which threatens his latest attempt to fly solo around the world.

The 58-year-old millionaire adventurer took his balloon to just 400 metres (1,300 feet) over the South Pacific from his cruising altitude of 7,000 metres (23,000 feet).

We would have faced a major line of thunderstorms

Mission director Joe Ritchie

Meteorologists at Mr Fossett's mission headquarters in the US city of St Louis told him to stay low to avoid getting sucked into an air stream that would have pushed him into dangerous weather.

Mr Fossett also slowed to about 34 km/h (21mph) but he had already passed the quarter mark in his attempt to be the first person to circumnavigate the world alone in a balloon.

He is predicted to reach the coast of Chile in about three days.

Joe Ritchie, the trip's mission director, said it would have been "a huge problem" if the balloon had got dragged into the weather system. "It would've cost us first a couple of days and then we would have faced a major line of thunderstorms," he said.

Meteorologists in the US will tell Mr Fossett when he can increase altitude

Mr Fossett took off smoothly from Western Australia in his Spirit of Freedom balloon on Wednesday.

Dodging the storm was his first big challenge of this attempt - a marked contrast to his previous trips which have suffered many problems including lack of oxygen and bad weather.

This time Mr Fossett has taken double the amount of oxygen, but the lower altitude has meant he has been able to take of his face mask and breathe real air.

His weather team will tell him when he can try to increase altitude again as necessary to clear the Andes mountain range.

If good conditions continue, his supporters say he could complete his round-the-world voyage in just 12 days - several days faster than predicted.