A British explorer has announced his plan to reach the North Pole by hot air balloon - a journey being described as the world's last great balloon challenge.

David Hempleman-Adams, 43, aims to complete Swedish explorer Saloman Andree's fatally unsuccessful attempt in 1897 to reach the North Pole by balloon from Spitzbergen, Norway.

It has been described by fellow explorers as the world's most dangerous balloon flight.

Mr Hempleman-Adams will be travelling alone in a wicker basket, 7ft by 4ft.

He will have to endure temperatures as low as minus 60 degrees centigrade at altitudes of up to 20,000ft.

"It is the last great uncompleted adventure from that heroic age of Scott and Shackleton, combined with a great aeronautical challenge," Mr Hempleman-Adams said as he unveiled his plans in London on Tuesday.

He said the journey would be the greatest and most dangerous challenge he had faced in 25 years of risk-taking.

"If we succeed, it will be the pinnacle of the adventurer's progress and prove yet again what we can achieve with the right team and motivation."

He admitted the trip was fraught with danger.

"The problem is once I get up to the North Pole - because the winds are so confused up there I could end up in either Canada, Russia or Alaska," he said.

"I could pitch into the freezing Arctic sea, and trying to land on the pack ice is going to be tricky."

The trip's flight director is Brian Jones, a pilot aboard the Breitling Orbiter balloon which circumnavigated the globe last spring.

Mr Jones has more ballooning experience than Mr Hempleman-Adams but said he would not attempt the trip himself.

"If he does come down on the ice he is completely on his own for a substantial period of time," Mr Jones said.

Mr Jones will be guiding the balloon through the chaotic Arctic winds from the Brittanic Challenge's control centre in Birmingham.

"If we can get the weather slot then the chances for success are quite good. There is a lot of luck involved," Mr Jones added.

Polar bear attack

Mr Hempleman-Adams will be carrying 20 day's worth of emergency rations, a tent and a rifle to defend himself against polar bear attack, in case he has to make an emergency landing.

He hopes to depart between the end of March and the beginning of May, depending on the weather.

Mr Hempleman-Adams is no stranger to the North Pole.

In 1998 he and his Norwegian partner, Rune Gjeldnes, walked there to complete the explorer's Grand Slam.

The pair walked to the North and South geographical poles, reached the North and South magnetic poles, and climbed the highest summit in each of the seven continents, including Mount Everest and Mount Kilimanjaro to claim that accolade.