JOHANNESBURG, JULY 17 -- A new wave of assassinations of African National Congress activists in neighboring Swaziland and elsewhere has given rise to fears within the outlawed guerrilla organization that South African security police have accelerated a campaign to break the movement's military capability.

Officials at the group's headquarters in Lusaka, Zambia, said today that increased attacks by hit squads operating across South Africa's borders appeared to be a fulfillment of President Pieter W. Botha's pledge in May to strike at the movement anywhere in the world.

The assassination of two top ANC officials and a woman companion last week brought to 11 the number of members of the group's military wing murdered in Swaziland in the last eight months. The three were killed when, according to witnesses, three white men in a South Africa-registered BMW sedan forced their taxi off the road and opened fire.

The victims included Cassius Make, 45, reportedly a high-ranking official in the group's military branch, Spear of the Nation. Also killed was Paul Dikeledi, 32, described as being in charge of ANC military operations in Transvaal Province, and a Mozambican woman, Eliza Tsinini.

As they have following similar assassinations, the South African police have refused to comment on allegations by the ANC that the gunmen were members of undercover police hit squads reportedly operating in neighboring black-ruled states.

ANC spokesman Tom Sebina said in a telephone interview from Lusaka today that the recent Swaziland attacks -- coupled with a car bomb attack in neighboring Botswana and reports from London of an alleged conspiracy to kidnap top ANC leaders there -- appeared to be part of a new South African police campaign to break the movement's military wing.

President Botha "said the fight against the ANC will be taken all over the world. We believe the escalation of this program is to satisfy his right-wing constituency. He seems to be fulfilling his . . . promises," Sebina said.

According to news reports from London, three men appeared in court yesterday charged with conspiring to kidnap senior ANC officials based there. The suspects were identified as Frank L. Larsen, 53, described as a psychologist, and his son, John, 27, both believed to be Zimbabwean nationals, and John R. Wheatley, 28, described as a British national. All were said to have made frequent visits to South Africa.

A spokesman for South Africa's National Intelligence Service denied that security services were involved in the alleged plot. "As a rule we don't comment on press reports, but should we be accused of such a plot then it is totally untrue because we are not involved at all," the spokesman said.

Tom Lodge, a political scientist at Johannesburg's University of the Witwatersrand who is widely recognized as South Africa's leading expert on the ANC, said he doubted that South African police were involved in the London incident.

"It sounds more like an adventure with a different agenda. Why would they do it? London is scarcely an absolute center of their {the ANC's} operations," Lodge said, speculating that "right-wing nuts" in British intelligence or South African mercenaries might be involved.

But Lodge said that the assassination of ANC members in Swaziland and other neighboring states could effectively hurt the movement's ability to wage guerrilla war inside South Africa.

He added, "It would be what I would do if I were involved in counterinsurgency: pull out or kill key operatives in one of the main centers for logistical and communications support."

Botswana, Lodge said, would be less of an undercover police target because the government there has been more cooperative in restraining ANC activities.

In addition to the Swaziland killings, ANC guerrillas inside South Africa have sustained major losses in recent months. Figures released earlier this year by Pretoria University's Institute for Strategic Studies show that up to 300 ANC operatives inside and outside South Africa have been killed.