United Nations, N.Y. — Prospects for a heated United Nations Security Council debate on Namibian independence are growing stronger, according to informed diplomatic sources. These sources say the Security Council probably will be convened in June at the request of the African states. The Africans will press the council to adopt sanctions against South Africa for its refusal to comply with Security Council Resolution 435, which demands an end to South Africa's occupation of Namibia.
The momentum toward a confrontation between the United States and its Western allies on the one hand, and the Africans on the other, is building rapidly.
The so-called ''nonaligned'' nations took up the issue of Namibian independence at their Delhi summit in early March, criticizing the United States effort to link the issue of Namibian independence with a Cuban troop pullout from Angola.
And in Paris next month, the Conference on Namibia is expected to further elaborate African complaints on the slow pace of action toward Namibian independence.
The Organization of African Unity is expected to send to the West another stern message at its May meeting in Ethiopia, asking for quicker movement on this issue.
If no progress regarding Namibia's independence has come about by June (and many analysts expect none), UN Secretary-General Javier Perez de Cuellar is expected to submit a pessimistic report to the Security Council, which would presumably attribute the lack of progress mainly to the insistence on the part of South Africa on linking Namibia independence to the Cuban troops in Angola.
Zambia will be presiding in the Security Council in June, and this would not make things easier for the US, Britain, and France - members of the Western ''contact group'' that is trying to work out a Namibian settlement. They are also permanent members of the Security Council.
There is little indication of progress in the two sets of bilateral talks that the Angolans have been periodically holding with South Africa on a possible cease-fire, and with Americans on withdrawal of Cuban troops, say high-ranking Western officials.
''These talks continue, but essentially what we are watching is a twin pair of cat-and-mouse games. South Africa and the US feel that time is on their side and that the Angolan mouse will eventually die. . . . The Angolan mouse feels that it must try and survive (Angola's economy is in shambles) and hope for better times. While it keeps talking to the two cats, the cats don't try and eat it,'' says a Western diplomat directly involved in the diplomatic process.
Behind the diplomatic rhetoric, key elements in the impasse on Namibia are:
* The determination on the part of the Reagan administration and South Africa to gradually rid southern Africa of Marxist regimes.
* The military and economic weakness of the African ''front-line'' states (Tanzania, Zimbabwe, Mozambique, Botswana, Zambia, Angola) that are pushing for Namibian independence, as well as their aversion to South Africa's apartheid system, their solidarity with the rebel group SWAPO (South-West Africa People's Organization), and their vulnerability to South African military incursions and dependence on the US in matters of trade and finance.
''The front-line states are telling us two things at the same time: They accuse us of dragging our feet concerning the implementation of the UN plan for Namibia, and they ask us to continue our efforts,'' says a member of the contact group.
In the end, the Africans may be persuaded at the Security Council to drop their push for sanctions. If they don't, the US is expected to use its veto to block them.