He made the comment to reporters in Moscow as he described the problems he met during his four-day, husky-drawn sled expedition to the North Pole, which he reached on Sunday before being helicoptered off the ice.

After his trip, during which he was alone but for his doctor, a Russian explorer, a British woman climber and four other companions, Albert expressed alarm about the signs of global warming and its effect on the Arctic.

Asked about his future plans he replied: "Perhaps a visit, but not an expedition, to Antarctica".

He told reporters of the "snow-covered compressed ice" that made travel "very difficult" and the lakes "hardly covered with ice" that had to be by-passed.

"Sometimes the snow and blocks of ice had to be moved to make it easier for the sleds to get through," he recounted.

"On several occasions we even had to lead the dogs by hand because they were scared to pass, since the gaps in the ice were too big for them."

"Once, just after we had passed over a sheet of ice, another sheet next to it, split away and within a few moments there were 40 to 50 centimetres (16 to 20 inches)" between the two pieces, Albert said.

"I want to thank the six dogs that made up my team: Charlie, Pyret, Fiona, Nelly, Edwin and Eros. They are the real heroes of this adventure."

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