Is South Africa calling West's bluff with offer to leave Namibia?

South Africa's apparent offer to let the West assume control of Namibia is seen here as serving one main purpose: to further the impression that Pretoria is willing - indeed eager - to quit the territory.

Prime Minister Pieter W. Botha has reportedly been making the offer during his current tour of Europe. In meetings with the leaders of Portugal, Britain, Switzerland, and West Germany, Botha has apparently offered to let any of the five Western nations that have negotiated for Namibian independence take over the territory's adminstration and defense. Those five Western countries are the United States, Britain, West Germany, Canada, and France.

The so-called Western contact group has been pressing Pretoria to relinquish control over Namibia (South-West Africa) since 1977.

There appears to be an element of brinkmanship in the offer. Botha reportedly told members of the press in Bonn, ''We have called their bluff and now they won't come out of the corner.'' He also was reported to have said the proposal had no time limit but ''they (the West) won't do it.''

Most analysts here do not expect any Western country to jump at Botha's offer. But it may be discussed informally at today's summit of the Western industrial powers in London.

Earlier this year Botha told the South African Parliament that Namibia had become a ''heavy burden'' for South Africa and that he wanted the issue of the territory's independence resolved ''one way or the other.''

The South African government has continued to harp on the theme that it wants out of Namibia. But Pretoria adds that free elections in Namibia remain impossible as long as an estimated 25,000 Cuban troops are stationed in neighboring Angola. The United States is spearheading Western negotiations for Namibian independence and it has echoed Pretoria's demand for a Cuban withdrawal as part of an independence plan.

The South African government here would not confirm that Botha had made the offer. Details of the offer are sketchy but reports from West Germany state that Botha still attached the condition of a Cuban withdrawal prior to turning over Namibia to any Western country or group of countries.

Botha's offer appears aimed at underscoring to the West the economic cost of administering Namibia and the need for substantial Western aid once the territory becomes independent. Botha claims South Africa gives Namibia over $500 million a year in economic aid and guarantees loans totaling close to $500 million.

Of course, a major expense incurred by Pretoria that would fall away at independence is the cost of its low-level war against SWAPO (South West Africa People's Organization) guerrillas, who are fighting for control of Namibia. Botha said Pretoria spends $400 million annully on the Namibian war.

Namibian independence has been high on the agenda of the West European leaders who have met Botha. The South African prime minister has promised while in Europe that the withdrawal of South African troops from Southern Angola would be completed within the next several days.

The Reagan adminsitration hopes this step will lead to movements on the Cuban question since Angola has said Cuban forces were necessary for protection from South African troops.