NEW YORK -- President Joachim Chissano of Mozambique has said in an interview that some of the recent acts of violence in Johannesburg's black townships may have been perpetrated by Mozambican rebels under the direction of "certain elements" of South Africa's security forces.

Questioned here last week, Chissano also said he believes that, in defiance of Pretoria's official policy, these same "negative elements in South Africa who are against change, change in South Africa and change in the region," are continuing to support the rebels in Mozambique's civil war.

Chissano's suspicions, if true, would indicate that the same "third force" that African National Congress leader Nelson Mandela has accused of fanning violence in the Johannesburg townships also is at work in Mozambique. This "hidden hand," as Mandela also has called it, appears to have erected hurdles for both Chissano and South African President Frederik W. de Klerk to clear, if the two leaders are to realize their professed desires for peace and political change in their neighboring countries.

Last month, six black men massacred 26 commuters and wounded more than 100 returning to the Soweto black township from Johannesburg. Without saying a word, they ran from car to car shooting and hacking with machetes, throwing many victims off the train. Mandela suggested that their silence was intended to hide that they were Mozambicans, who speak Portuguese.

Mandela also said the indiscriminate killing aboard the train resembled tactics used by rebels of the Mozambique National Resistance, or Renamo, as it is known by its Portuguese acronym, to spread panic during its bloody, 15-year attempt to overthrow the Mozambican government.

Asked about Mandela's statements, Chissano said, "Yes, it's possible . . . {that} Renamos {are} being utilized in South Africa." The Mozambican president suggested further that "not only Renamo, but other {foreign} elements" may be taking part in South Africa's township violence.

Referring to attempts by previous South African governments to destabilize neighboring countries harboring ANC guerrillas, Chissano said: "We know that the elements of other countries . . . were working for the South African Defense Forces in the past. There were brigades, special brigades {training} there for the destabilization purpose, and these people were not thrown out {of South Africa}.

"They are Angolans, Mozambicans, Zimbabweans -- and other nationalities have been involved in this destabilization. So it is not impossible to have Renamos or ex-Renamos . . . operating there.

"I feel that the government of South Africa is not supporting Renamo" any longer, Chissano said, "but I feel that there are negative elements in South Africa . . . maybe some elements" within the armed forces that still might be supplying or helping the Mozambican rebels "somehow."

Asked if the "negative elements" supplying Renamo were the same "certain elements" that Mandela has accused of being behind the township violence, Chissano said, "Yes, I suppose so."

Mandela has blamed much of the township violence on elements of the South African security apparatus trying to derail de Klerk's constitutional changes, which he is negotiating with the ANC, by showing the black nationalist movement incapable of maintaining order among blacks. After the train massacre, de Klerk admitted that a "third force" seemed to be playing an organizing role in the violence, but he did not go as far as Mandela in accusing the security services.