JOHANNESBURG, FEB. 19 -- A simmering intratribal feud between the ostensibly independent South African "homelands" of Ciskei and Transkei exploded into open warfare early today as truckloads of armed men with machine guns and mortars attacked the palace of Ciskeian President-for-Life Lennox Sebe in an apparent attempt to overthrow his government.

The clash provided a source of embarrassment for the government of South Africa, which has attempted to present tribal homelands as a model of its policy of "separate development," a cornerstone of apartheid.

During a 30-minute gun battle, at least one person was killed and several others wounded, according to a government spokesman in Ciskei. Officials in Bisho, the capital of Ciskei, said the attackers were beaten back and that an armored truck used in the attack was captured.

The attackers apparently intended to capture Lennox Sebe and use him as a hostage to force a merger between the two homelands, said Ciskeian Information Minister Headman Somtunzi in a telephone interview from Bisho. Sebe and his wife, who were in the palace at the time, were unharmed, the officials said.

The foreign minister of Transkei, a nominally independent homeland within South Africa, said he knew nothing about the attack. The minister, Caleb Songca, claimed that no soldiers from the Transkei Defense Forces were involved in the fighting.

Somtunzi said that captured vehicles used in the attack had Transkei registration plates, and that documents seized during the battle indicated that the attackers were supported by mercenaries in the Transkei Army under Maj. Gen. Roy Reid-Daly, a former regimental sergeant-major in the Rhodesian Army's elite Selous Scouts and one of the most widely known white mercenaries still active in Africa.

"They were attempting to kill our president and overthrow the government. We are fully mobilized for another such attack, although we fear it will be worse next time," said Somtunzi.

Somtunzi said that only three of the 25 attackers managed to get into the yard surrounding the palace during the 3 a.m. attack. He said one was killed, one critically wounded and another captured.

Ciskeian officials said an armored vehicle bearing Ciskei Defense Forces markings was used in the attack.

The captured man was identified by Somtunzi as Maj. Nkosinati Sandile. He is a former Ciskeian Army officer who recently was arrested in Transkei and who claimed in a subsequent press conference there that he had been dispatched personally by Sebe on a mission to murder or abduct Sebe's brother, Charles, who has attempted on several occasions to stage military takeovers in Ciskei. In September, Charles Sebe made a spectacular escape from a Ciskei prison with the help of Transkei security forces.

The Ciskei president denied that he had ordered an assassination attempt.

The bizarre warfare between the two South African vassal states, which are among four tribal homelands that have accepted the status of independent "republics" -- but which have not been recognized by any government other than South Africa -- erupted after the Ciskeian government announced on Wednesday that all Transkeians in its territory must leave by Aug. 31, before an expected invasion by the tiny Transkei Army.

The two homelands, in which most of South Africa's 6 million Xhosas hold citizenship, are impoverished one-party states ruled by strongmen who openly cooperate with South Africa's white government. They are separated by a 15-mile-wide white-controlled buffer just west of the Indian Ocean port city of East London.

Beneath the surface of the feud within the Sebe family lies increasing unrest in the quasi-state of Ciskei, whose nearly 1 million population lives for the most part in abject poverty and nearly 50 percent unemployment. The per capita gross national product is the lowest of the four self-proclaimed independent homelands -- Ciskei, Transkei, Bophuthatswana and Venda -- at about $175 a year.