Britain considered closing its bases in Antarctica in the 1950s due to the high costs of maintaining them and aggressive territorial claims from Chile and Argentina, previously secret papers showed on Monday.

The revelations in documents released by the National Archive come as Britain and other nations weigh extending their claims to the seabed around Antarctica by a May 2009 deadline.

The seabed under the vast ice-bound continent is thought to hold rich mineral resources, and scientists fear there could be a subsea land grab sparking the friction between nations that was seen on the surface half a century ago.

The documents were released under a rule that keeps some sensitive government data under lock and key for 50 years for reasons of national security.

"It is possible that the foreign secretary may recommend to his cabinet colleagues that the United Kingdom should withdraw from the Falkland Island Dependencies," reads a briefing in March 1957 to the Lord President.

The Antarctic peninsula - the British sector of the world's coldest and driest continent - was formerly known as the Falkland Island Dependencies.

The question was considered by the government on March 14, 1957 and rejected.

"The conclusion was reached that it would be unsound to consider making any change in the status of the United Kingdom sector," said another note.

ECONOMIC BENEFITS

Britain wanted to maintain its influence in the Antarctic but avoid the costs as the United States and the Soviet Union increased their activities in the area, and it faced territorial disputes with Argentina and Chile.

The report said Britain was spending 160,000 pounds a year maintaining its 10 Antarctic bases and needed an ice breaker vessel that would have cost about 3 to 4 million pounds to keep pace with the activities of its main rival Argentina.

However, suspecting the region might harbour vast mineral wealth, Britain also wanted to protect the economic benefits that might flow from them.

"As an industrial state, we cannot afford to be indifferent to the existence of a possible reserve store of vital new minerals," the document read.

Britain's plan B was to propose placing the entire Antarctic continent under some form of international control.

This came in any case two years later in the form of the 1959 Antarctic Treaty which prevented all exploitation of oil, gas and minerals other than for scientific research.

Argentina, Australia, Britain, Chile, France, New Zealand and Norway - all close to Antarctica or with historical ties - made claims before the treaty took effect. Moscow and Washington did not make claims but reserved the right to do so.