Scientists working in Antarctica have repositioned the special marker post that records the exact location on the Earth's surface of the South Pole.

The special ceremony, which is always carried out on 1 January every year, is necessary because the ice pack is shifting. Over the course of 12 months, the pole, which has an inscribed plaque on top, moves by approximately 10 metres.

Researchers based at the US South Pole Amundsen-Scott Station used the orbital satellites of the Global Positioning System to measure the new location to an accuracy of two centimetres.

This is known as the Geographic South Pole - the place where all the longitude lines converge.

A formal marking ceremony in front of the base population and live BBC cameras was then conducted at 1530 GMT on Friday, just a few hours after local midnight on the first day of the new year.

Line of posts

Larry Hothem from the US Geological Survey planted the post on a day when temperatures were down to around -30 degrees Celsius.

"We wish everyone, all members of the scientific community in the Antarctic and the support people in the Antarctic programme, a very happy New Year, happy century and happy millennium."

The marking ceremony has been taking place since the mid-1980s. A line of posts shows how the ice has moved over the years.

Both Roald Amundsen, who was first to reach the pole in 1911, and Robert Scott, who got there a month later, used an astronomical method to locate the bottom of the Earth.

Their mark would have been accurate to about 2-300 metres, but because of the shifting ice and accumulation of snow is now probably some 1,000 metres away and six metres below today's official position.