JOHANNESBURG, NOV. 14 -- President Pieter W. Botha and his senior Cabinet ministers sought today to dampen domestic criticism of South Africa's deepening involvement in the Angolan civil war, warning that public debate would jeopardize military operations there.

It also was disclosed that Botha and five Cabinet ministers visited southern Angola recently to underline their support for the Army's incursion. The officially announced number of South African soldiers killed in Angola in the past two weeks rose to 23.

Botha defended the controversial intervention, which Pretoria says saved anticommunist rebels from a defeat at the hands of Cuban- and Soviet-backed government forces in southeastern Angola.

"We do not want to act recklessly," Botha told a convention here of the Transvaal Province National Party, "but if South Africa had not done what it was able to, the lives it would have otherwise saved would have nothing left. I can only give you this assurance: South Africa's security is in the best hands imaginable. They {the South African Army} are all responsible men who are not warmongers."

His remarks came as Defense Minister Magnus Malan disclosed that Botha and five senior Cabinet ministers had "very recently" visited Army units in southern Angola. He said Botha's unusual visit had shown the president's "involvement and personal responsibility."

English-language newspapers critical of the government, liberal opposition politicians and antiapartheid activists warned this week that South Africa was in danger of being drawn into a wider conflict not only with the Marxist government in Angola, but with Angola's principal patron, the Soviet Union.

The critics also have accused Botha and Malan of withholding essential information about the intervention from the South African public.

The country's largest daily newspaper, the Johannesburg Star, warned that involvement in Angola was "entering a new and dangerous dimension." Business Day, the leading financial newspaper, said, "Once again our forces are engaged in a conflict about which South Africans themselves know virtually nothing."

Speaking to the Transvaal convention, Malan noted pressure from the press for details of the Army's activities, but replied, "Nowhere in the world are operations of this nature broadcast from the clock tower."

He said that if the Angolan forces were not stopped, South Africa could become vulnerable to attack from neighboring Namibia or from Botswana, Zimbabwe and Zambia.

He apparently was referring to the presence in Angola of guerrillas of the African National Congress (ANC), the main force battling white minority rule in South Africa, and the South-West Africa People's Organization (SWAPO), which seeks to seize power in South Africa-controlled Namibia.

Malan did not say when Botha went to southern Angola, or where he visited, but he said that the other Cabinet members included Education Minister Frederik W. de Klerk, Foreign Minister Roelof F. (Pik) Botha and Finance Minister Barend du Plessis.

To illustrate that the government was acting "as a unit" in its support of the military intervention, Malan said he also took a group of members of Parliament to Angola.