The team will rise from 7,000ft to 40,000ft to catch the 150mph winds which will propel them on their attempt to capture the last great aviation record.

The balloonists took off from southern Spain on Wednesday.

They have had to wait five days for the right moment to enter the jet-stream so they could avoid prohibited Chinese airspace.

A spokeswoman for the Cable and Wireless-sponsored team said: "Once they are in the jet-stream they will literally fly."

After a text-book take-off, the balloon headed south.

But it drifted from its intended course, which would have taken it further towards the Canary Islands.

The pilots had to head south-west before doubling back on themselves and travelling north-east to avoid China.

Balloons banned

Beijing's refusal to grant them permission will add seven days to a journey that has already defeated several teams.

All British balloons were banned from Chinese air space after Virgin tycoon Richard Branson entered a restricted air corridor during his round-the-world attempt last December.

On Saturday, the two men carried out a 10-minute "sky-walk" on the outside of the capsule at 8,000ft to carry out repair and maintenance.

If all goes well, a successful touchdown could come in the North Sea or in the Mediterranean anywhere from 12 to 25 days after lift-off.

Circumnavigating the globe non-stop in a balloon is one feat yet to be accomplished. The Anheuser-Busch company is offering a $1m prize to the first team that makes it.