United Nations, N.Y. — Antarctica, the seventh continent - larger than the United States and Mexico together - is rapidly turning into a major international bone of contention. For the second year in a row the United Nations is turning its attention to the question of Antarctica's ownership. Recent completion of the Law of the Sea Treaty has given impetus to the largely Malaysia-led campaign on Antarctica.
At this stage, diplomats on both sides of the fence move cautiously and speak with low voices. Tempers have not yet flared. ''A whispering match has begun. The shouting match may still be a couple of years down the road,'' says a well-placed observer.
The stakes are high: Antarctica is believed to be a gold mine in mineral resources.
On this issue, the United States and the Soviet Union stand shoulder to shoulder. They are determined to keep the immense, frozen, strategically located , mineral-rich piece of real estate out of the UN's jurisdiction and, if possible, out of its scrutiny.
In a rare show of comradeship last spring, US deputy representative Charles Lichenstein and Soviet deputy representative Seregeyezich Ovinnikov together visited UN Secretary-General Javier Perez de Cuellar (who admitted to being pleasantly surprised to see them holding hands, diplomatically speaking, rather than waving fists at each other), to stress that their countries were adamantly opposed to UN involvement in Antarctica.
Since 1959 the world's coldest continent (5.1 million square miles or one-tenth of the earth's land surface) has been administered by 12 original signatories of the Antarctica Treaty - Australia, New Zealand, Chile, Argentina, Britain, Norway, the US, the Soviet Union, South Africa, Japan, France, and Belgium - plus four recent new ''members of the club,'' Poland, Brazil, India, and West Germany.
The treaty essentially demilitarizes Antarctica and provides for, regulates, and supervises scientific research in the area.
The treaty does not, however, settle the legal status of Antarctica. It simply freezes the various territorial claims. Brazil, Argentina, Uruguay, Norway, Australia, France, and Britain have made territorial claims on Antarctica. Some claims overlap. One large slice (15 percent of Antarctica) has not been claimed and is considered to be potentially the US sector.
The Soviet Union does not recognize any claims and reserves its rights to lay claims.The US also rejects all existing claims and favors free access to the whole of Antarctica for itself.
Argentina calls its share ''Antarctica Argentina.'' Claims are based on territorial proximity or on substantial scientific research undertaken in the past (the US, France, Britain, Norway, India, and Brazil).
Neither does the Antarctica Treaty settle the question of who is to exploit Antarctica's mineral wealth and who should profit from it.
Its known or suspected wealth includes offshore resources such as oil; deposits of manganese nodules; on-land (under the icecap) resources such as iron , coal, copper, nickel, gold, and uranium; and living resources such as krill, seals, and squid. The engineering capacity to exploit these minerals may be only five to 10 years down the road, according to some American and West European experts.
Should Antarctica's wealth be shared only by the 16 consultative parties? Should it be considered as ''the common heritage of mankind'' and should all nations of the planet, to some degree, benefit from its exploitation?
''Don't touch the treaty,'' say the treaty members.
A representative of one consultative party says, ''It has worked well. It has kept nuclear weapons out of Antarctica. It has maintained international harmony in Antarctica.'' If any attempt is made to share Antarctica more widely, it must be done by the consultative parties and not the UN, he says.
Others agree with Singapore diplomat Tommy Koh, who two years ago said several questions deserved to be asked:
* Why do the consultative parties meet in secret and make no formal reports of their decisions?
* Why does the treaty maintain two classes of members?
There are 16 consultative members who have all the power. But another 16 - Bulgaria, China, Czechoslovakia, Denmark, Finland, East Germany, Hungary, Italy, the Netherlands, Papua-New Guinea, Romania, Spain, Uruguay, Peru, Cuba, Sweden - are classified as nonconsultative and act as mere observers. They do not vote nor sit in on the consultative parties' meetings.
* Can the treaty forever remain in the hands of a small club of industrial nations?
* Will the world accept this situation as legitimate?
Last year the UN took a seemingly innocuous iniatitive. It requested the secretary-general to prepare a factual, comprehensive, objective study of all aspects pertaining to the Antarctica question.
This report (nearly 200 pages) has now come out and describes many factors (legal, scientific, economic) of the treaty without taking sides. Meanwhile Malaysia's prime minister, Dr. Mahathir bin Mohamad, told the General Assembly this fall that ''while the treaty system has done a lot of good, we are seeking to build a broader basis for international cooperation in Antarctica.''
Dr. Mahathir has proposed the establishment of a ''special committee on Antarctica,'' with the mission of studying the subject in depth and arriving at a consensus on the objectives of a new administration of Antarctica and the machinery to achieve such an objective.
The committee should in no way prejudge the issue, says Malaysia's UN ambassador, Azraai Zain. It should seek to determine whether there is an agreement among UN member states on how to best protect the environment in Antarctica and on how to most efficiently and fairly share its resources.
The consultative parties worry that ''this committee would become a slicing machine which would slowly cut the treaty to shreds and lead to another Law of the Sea Treaty,'' says one West European diplomat.
Whether the committee will be set up this year or in a year from now does not make much difference. In the end, most analysts say, there are only three possible solutions to the question of Antarctica:
* The treaty powers may recognize that the world political climate has changed since they signed the treaty 25 years ago and decide to establish a new minerals regime that would provide for equitable sharing of Antarctica's resources in the world community.
* The UN will bring the entire Antarctica question under its jurisdiction, arguing that the treaty's legal foundations are dubious. (''They remind one of the Berlin Treaty of 1884 by which a handful of European powers carved up Africa in zones of influence for themselves,'' says an African delegate.)
* A compromise may be worked out by which the existing treaty would be preserved for its present objectives except in the area of resources. A separate system of management of resources would be set up and open to all nations, a UN official suggests.
The next consultative party meeting is scheduled for Brasila next March. Observers may be looking for a public split in the group between those who want to open the forum (''doves'') and those that don't (''hawks''). So far, the doves (Norway and New Zealand) and the hawks (Chile, the US, and the USSR) have not been able to agree on whether they should accommodate others.
''If they don't, a major confrontation between the haves and the have-nots of the world may be unavoidable,'' says one consultative party diplomat. Meanwhile Antarctica makes for strange bedfellows since the USSR and the US, Britain and Argentina act as close partners.
China is expected to become the 17th full-fledged consultative party member in the near future. Many Africans distrust this select club, which has so far accepted only one African nation: South Africa. Peru will soon be the first nonconsultative treaty member to give up its position in order to register its dissatisfaction with the lack of access the nonconsultative treaty parties have to the decisionmaking process.
''We thought we were taken on board by the consultative parties, but we are simply being co-opted'' says another nonconsultative Treaty representative.