Mr Branson said: "I am slightly biased, but I think it is an incredible achievement - the last great aviation record left."

The British millionaire has made four unsuccessful attempts at the record himself, and said it was "most likely" he would abandon any future attempts.

He had been planning a fifth attempt, which would have set out from Argentina next month.

Challenger flew over Mount Fuji

The pilots of the Breitling Orbiter 3 balloon - Briton Brian Jones and Swiss Bertrand Piccard - were on Friday on course to cross the finishing line for the first non-stop circumnavigation in north Africa at Saturday lunchtime.

Mr Branson, who was the first to cross both the Atlantic and Pacific oceans by balloon, said he had already sent the team a note saying it was "quite magnificent what you've achieved".

And he said he hoped to fly to north Africa to meet the balloon.

But that did not stop him from joking that he would use pilots from his Virgin Atlantic airline to try to thwart the pair, who at the time were floating toward northwest Africa.

Trans-global balloon race

"We are, at the moment, strapping on guns on the Virgin 747s, scrambling the fleet to Africa," he said.

"We hope to intercept the balloon before it reaches its end."

He paid tribute to Piccard and Jones, who he said had completed "such a magnificent flight and have beaten us today.

Branson: 'It is an incredible achievement."

"It has been a magnificent flight and they have tried as long as we have to get around the world.

''Bertrand has got a fantastic history of both father and grandfather as great balloonists, he is a worthy person to hold the record."

The businessman said he now plans to turn his attention to organising a trans-global balloon race, because it had been proven that a balloon could be designed to circumnavigate the globe.

Just before the Breitling balloon took off from the Swiss Alpine ballooning centre of Chateau d'Oex, Brian Jones said: "I want to land near the Egyptian pyramids in Giza."

But he told reporters they planned to swing south-west over Morocco before turning east on their epic flight, and said: "Maybe we'll drop something or other on Richard Branson's landing strip just to say hello."