Stakes in Namibia raised as Angola-S. Africa conflict flares. . .

It appears that positions are hardening and that the stakes are being raised in the long-simmering dispute over independence for Africa's last piece of colonial real estate, Namibia.

Oddly enough, Namibia (South-West Africa) itself is quiet. But it is being used as justification for mounting conflict in neighboring Angola, where the rivalry between the two major opposing forces of southern Africa appears to be intensifying.

Those opposing forces are the white nationalism of South Africa and the brand of black nationalism represented by both the Angolan government and the SWAPO (South West Africa People's Organization) guerrilla movement fighting for control of Namibia from bases in Angola. Both are perceived by South Africa as major threats because of the support that Angola, and to a lesser extent, SWAPO, receive from the Soviet Union.

South African Foreign Minister Roelof Botha has disclosed that the Soviet Union recently (last November) warned South Africa that the Namibian situation had become ''acute'' and that Pretoria's military activity in Angola and support for antigovernment rebels in that country were unacceptable.

The Soviet warning also informed South Africa that the US initiative to get a withdrawal of Cuban troops from Angola as a condition for settlement in Namibia would fail, according to Mr. Botha. South Africa administers Namibia in defiance of the United Nations. There are an estimated 25,000 Cubans supporting the Angolan regime and both South Africa and the US have said Namibian independence cannot go ahead without an agreement on their withdrawal.

Analysts have regarded the Soviet warning as a signal that Angola's ruling MPLA (Popular Movement for the Liberation of Angola) is increasingly pressured from the rebel UNITA (National Union for the Total Independence of Angola) movement. South Africa is widely acknowledged to support UNITA, led by Jonas Savimbi, although the extent of support is unclear.

Despite the Soviet warning of last November, South African troops in December mounted an offensive into southern Angola allegedly against SWAPO. At the request of Angolan President Jose Eduardo dos Santos, the UN Security Council met this week to discuss this. The South African offensive appears to be continuing.

The concern expressed by Western diplomats here is that the South African offensive - although perhaps justified in military terms - could worsen the situation in Angola by encouraging more Soviet or Cuban involvement.

One glimmer of hope as seen by these diplomats is the South African offer of a trial ''disengagement'' of its troops from south Angola and Angola's counteroffer.

The conditions set by both South Africa and Angola are poles apart. South Africa is demanding that Angola ensure that its own troops, SWAPO, and the Cubans do not ''take advantage'' of a pullback with any actions that would ''threaten'' Namibians. Angola says a cease-fire is fine - if as South Africa agrees to follow it with quick implementation of the independence plan for Namibia.

The Angolan offer bypasses the Cuban troop issue and is rejected by South Africa. Still, diplomats are encouraged that Angola made a counteroffer after an initial rejection. They hope new talks may take place.

Analysts here also believe that there may have been subsequent contacts between South Africa and the Soviets, which some see as a hopeful sign. The assumption that further meetings have taken place is based on Foreign Minister Botha's refusal to deny that subsequent contacts have occurred.

At best, Western diplomats here portray the process of lessening tensions between South Africa and Angola as an uncertain one. They see at least the possibility that a cease-fire could lead to Namibian independence.

As one diplomatic source put it, a cease-fire could ''change the course of events.'' The scenario he saw as feasible was a cooling off period between Angola and South Africa leading Angola to restrain SWAPO and South Africa to restrain UNITA. This could bolster the MPLA regime in Luanda, Angola's capital, and give it confidence to consider a withdrawal of Cubans.

But analysts here see many potential pitfalls to that scenario. Analysts wonder how much freedom of action Luanda has from the Soviet Union. They wonder how much control Angola exercises over SWAPO.

Analysts also wonder whether South Africa can substantially restrain UNITA now that it has its own momentum. Some feel that even with a cutoff of South African assistance, UNITA could carry on for some time.

In recent months it appears all sides have been emphasizing military solutions. UNITA made dramatic gains in an offensive in August and appears convinced that only military pressure will give it a stake in the government. Luanda has given no signals that a reapproachement with UNITA is likely. This pattern appears likely to pour cement on the feet of the Cubans, and further stall a Namibian settlement. That encourages South Africa to keep hammering SWAPO militarily.