U.N. and Western officials, heartened by South Africa's acceptance of a demilitarized zone between Angola and Namibia (Southwest Africa), are now prepared to move ahead with their plan for Namibian independence.

The next move, they say, is likely to be the beginning of "technical discussions" to work out the remaining military and political details of the demilitarized zone, a concept first proposed by the Angolans in August.

These talks could involve the dispatch of U.N. military officials to South Africa, Zambia and Angola to work out the specifics of the DMZ proposal.

The South African statement accepting the concept of a demilitarized zone reached the United Nations on Wednesday, just after the break-through in London on the Zimbabwe-Rhodesia peace talks, and just before the annual General Assembly debate on Namibia.

Western officials expect progress on Namibia to be linked to Rhodesia, as both the South Africians and the front-line states look over their shoulders at what is happening to the north.

The South African statement was critical, but Western officials who have been working on the independence plan for three years view it as positive. "We are back in business," said one. "It's something we can work with," said another. The five Western countries negotiating the Namibia agreement are the United States, West Germany, Britain, France and Canada.

These officials cautioned that further progess would depend on a low-key outcome of the U.N. debate on Namibia, and the private acceptance by the front-line states and the South African People's Organization, the Namibian liberation movement, of the South African statement. But in the view of the West, Pretoria's stand eliminates one of the last obstacles to the establishment of a U.N. peace force and observer corps which would supervise elections and the transition to independence for the territory now ruled by South Africa.

One remaining sticking point appears to be South Africa's demand that SWAPO'S guerrillas be disarmed one week after elections in Namibia -- something SWAPO has not yet agreed to.

Other South African concerns included the conditions of deployment of the U.N. peace force and the retention of some South African bases in the demilitarized zone, but Western officials suggested that these could be resolved without difficulty, given the will.

In the assembly debate, SWAPO representative Peter Mueshihange said that the South African statement was a "far cry" from what had been expected, and must be "treated with the contempt that it deserves."

But the public response of SWAPO was significant "only if they are also adamant in private," said one Western diplomat.

The Zambian representative, Paul Lusaka, was more positive. The South African statement, "constitutes a conditional acceptance of the concept of a demilitarized zone, and will require further study."