Two guerrillas were killed by security forces this week after negotiators had worked out a plan for the insurgents to withdraw safely to Angola, a territorial official said Friday.

Gerhard Roux, spokesman for the South African-installed administrator of Namibia, confirmed the deaths, which were reported by a South African newspaper Thursday. He said details would be available later Friday.South African Foreign Minister Pik Botha said about 350 guerrillas of the South-West Africa People's Organization had withdrawn and about 900 remained in Namibia as of Friday, a day before a deadline for them to leave.

He said about 1,600 guerrillas infiltrated into northern Namibia beginning April 1, the first day of a cease-fire and a yearlong, U.N.-supervised process to make the territory independent. During the next eight days, 263 guerrillas and 27 members of the South African-led security forces reportedly were killed in fighting.

Botha's estimate of SWAPO infiltrators was lower than previous South African estimates of 1,900. He said 22 had been captured.

Last weekend, South African, Cuban and Angolan officials worked out an arrangement guaranteeing safe passage for guerrillas to Angola if they reported to U.N.-monitored checkpoints. As of this morning, however, only five guerrillas had reported to the checkpoints - the others who withdrew apparently did so on their own.

A U.N. official, Cedric Thornberry, said Thursday the insurgents probably were reluctant to surface because of the "menacing presence" of security forces near the assembly points.

The cease-fire has not been reinstated since last week's fighting, although South Africa has said its forces would fire at guerrillas only if attacked.