The pilots of the Anglo-Swiss round-the-world balloon are planning a daring climb out of their capsule to clear massive icicles weighing down their craft.

Briton Brian Jones and Swiss team-mate Bertrand Piccard have slowed their Breitling Orbiter 3 balloon as they prepare to climb out of their capsule and remove the 10ft spears of ice by hand.

Bertrand Piccard (left) and Brian Jones plan daring sky-walk

Jones and Piccard will take it in turns to leave their capsule on Thursday to carry out the two-hour task. Harnessed to the balloon, they will be dangling more than 6,000ft above the Sahara desert.

But a spokeswoman at the team's Geneva control centre insisted the sky-walk near the town of Taoudenni, in Mali, would present little danger.

"This is something that we expected to have to do, and the two pilots have trained for the job and have all the necessary equipment, so it is not very dangerous," she said.

Rivals Andy Elson and Colin Prescot, in the Cable and Wireless craft, have survived heavy turbulence over Vietnam to keep alive their hopes of becoming the first to circumnavigate the world by balloon.

The two Britons, who have already shattered existing distance and endurance records for ballooning, were resting on Thursday morning after encountering "some of their bumpiest flying of the journey", said mission control in London.

Chinese ban

Elson and Prescot have successfully edged their way around Chinese airspace, after the country banned British balloons from overflying it.

The ban has been in place since Richard Branson's ICO Global Challenger entered Chinese airspace in December.

But the Anglo-Swiss balloon has permission to cross the country, which gives it a significant advantage in its race with the Cable & Wireless craft.

The Cable and Wireless balloon has now been airborne for almost 16 days and is flying at 30mph and 27,0000ft over the South China Sea.

It is almost half way and 9,500 miles of the way through its planned circumnavigation.

The C&W balloon

The Breitling Orbiter 3 launched from the Alpine village of Chateau d'Oex in Switzerland on Monday morning in an attempt to catch the C&W team, who took off from Almeria, southern Spain, on 17 February.

The C&W team have allowed 25 days - including the lengthy detour - for their flight, compared to Piccard and Jones' optimum 16 days.

Elson and Prescot are flying towards Japan where they hope to catch a fast-moving, high-altitude stream of air to carry them over the Pacific at speeds up to 100mph.

It will hopefully deliver them to Canada in less than four days.

The Breitling crew hope to dramatically increase speed to 190mph by picking up a jet-stream high over Mauritania.

There have been approximately 20 previous attempts to fly around the world in a balloon, all of which have failed.