The planned route

He is flying at about 5,000ft, in temperatures of -25C, and at an average speed of 11mph.

Denise Bishop, from the flight control centre at Wythall, in Worcestershire, said: "He had around 3 hours sleep last night, and he's eating and drinking. He's knackered but he still has his sense of humour."

The 43-year-old adventurer told the control centre he was relieved to have covered the 200 miles of open water between Norway and the ice pack.

In a radio message, he said: "If I'd have crashed into the Arctic Ocean, survival would have been difficult.

"Thank God that part of the voyage is behind me and I have solid ice pack below. Now I can look forward to reaching the pole."

The feat which first got him into the record books - the UK solo ballooning record - had stood for more than 20 years.

Mr Hempleman-Adams aims to be the first person to complete Swedish explorer Saloman Andree's fatally unsuccessful dream of 1897 to reach the pole by balloon.

Polar bear attack

The 1,500 mile flight has been described by fellow explorers as the world's most dangerous balloon flight.

He is travelling alone in a wicker basket, 7ft by 4ft, and will have to endure temperatures as low as -60C at altitudes of up to 20,000ft.

Equipment on board includes a sledge, tent, shotgun, rations, sleeping bag and flares, and a dinghy in case Mr Hempleman-Adams has to ditch the balloon in icy waters.

He also has a rifle to defend himself against polar bear attack.

The Roziere balloon is of a design similar to the Breitling Orbiter balloon which went round the world non-stop in 1999, but is a tenth of its size.