The South African government announced tonight that King William's Town will not be handed over to Ciskei when that black homeland becomes a constitutionally separate state on Dec. 4.

The announcement by Piet Koornhof, South Africa's minister for cooperation and development, less than two weeks before the general election, overturns one of the key recommendations of the Van der Walt Commission on homeland consolidation.

Apart from the coastal city of East London, King William's Town is the only commercial center of any significance near Ciskei. Koornhof's announcement was greeted by loud applause at a meeting in the town, where strong white opposition to incorporation into Ciskei has been a major issure in the campaign leading up to the April 29 elections.

The deputy chief minister of Ciskei, the Rev. W. M. Xaba, said "We do not want our independance to be based on a hope of getting King Willam's Town."

The official opposition, the Progressive Federal Party, is continuing to step up its attacks on the government's race policies.

Opposition leader Frederick Van Zyl Slabbert, challenged Koornhof to stop arresting blacks caught without their government-issued passbooks until after the report of a committee reviewing major draft legislation affecting blacks. Statistics published by Prof. Michael Savage, of the University of Cape Town, show that 12,568,572 black Africans have been prosecuted or arrested under the pass laws since the Nationalist Party came to power in 1948.

The Progressive Party is campaigning hard on such issues. In advertisements headlined, "The Debate You Won't See on TV: Slabbert-Botha," it cites reports that 50,000 children died from starvation last year in rural areas. The party also quotes a Department of Health report that half of the 2-year-old and 3-year-old children in Ciskei are undernourished.

The fact that the Progressive Party is attacking the government from the left on some of the issues that the Herstigte Nasionale Party is using to attack it from the right poses a dilemma for the ruling Nationalist Party, observers believe.

The hard-line Herstigte has been accusing the government of doing too much for blacks by spending white citizens' taxes on them. If the government tries to answer the Progressive Party's charges its risks playing into the hands of the Herstigte. But if it fails to answer them, it could be condemned for not living up to its promises to move away from racial discrimination.

Meanwhile, there were these related developments:

The U.S. State Department Friday rebuked South Africa for revoking the passport of Anglican Bishop Desmond Tutu, the general secretary of the South African Council of Churches and an outspoken critic of that country's policy of racial separation.

State Department spokesman Dean Fischer said actions such as lifting Tutu's passport are "not helpful" because the inhibit communications with concerned outside observers.

Rep. Howard Wolpe (D-Mich.), chairman of the House subcommittee on Africa, also protested the move. Wolpe issued a statement calling Tutu "a leading black moderate within South Africa" and warning that efforts to silence him "will greatly reduce South Africa's chances for peaceful change."

During a visit to the United States last month Tutu said it would be a mistake for the Reagan administration to support the Pretoria govenment, as this could lead South Africa's blacks to resort to arms and seek support from communist governments.