JOHANNESBURG, South Africa (AP) _ Patrick Mphephu, the authoritarian president-for-life of the tiny black homeland of Venda, died Monday at the age of 63.

Mphephu, Venda's first and only president, died at a Pretoria hospital of ''multiple organ failure,'' the South African Foreign Affairs Department said.

Finance Minister Frank Ravele was named acting president.

South Africa's white rulers considered Mphephu a valuable and cooperative ally, but black activists condemned him for repressing dissent in Venda, the smallest and least viable of South Africa's four nominally independent tribal homelands.

No foreign country has recognized Venda since it was declared a republic in 1979. It has about 500,000 residents, many of them migrant laborers who work far from the territory, and occupies about 2,500 square miles in the northeast corner of South Africa.

South Africa's foreign minister, Roelof F. Botha, described Mphephu as ''loyal friend of South Africa who believed in cooperation rather than confrontation and took a firm stand against terrorism.''

Anti-apartheid leaders and human rights groups have characterized Venda authorities as ruthless in suppressing political dissent.

One prominent target of Mphephu's regime was the Rev. Tshenuweni Farisani, senior official of the Evangelical Luthern Church in Venda. He has been detained four times and says he was tortured during three of the detentions.

Mphephu, who had only a primary school education, headed a one-party state with strong backing from traditional chiefs and headmen of clans.

In the 1970s, Mphephu's party lost elections but retained power by jailing its rivals. He became the territory's paramount leader in 1950.