JOHANNESBURG, MARCH 1 -- The South African government extended its clampdown on opponents of apartheid today, introducing legislation that would prohibit the use of donations from abroad by any individual or group for "political aim or object."

The move followed a decision by the government last week to ban the activities of 17 leading antiapartheid groups, including the United Democratic Front, and severely restrict the country's largest labor movement, the Congress of South African Trade Unions.

The newest measure, called the Promotion of Orderly Internal Politics Bill, also provides that any person who "says or does anything" that can be construed as fomenting hostility or violence between racial groups will be liable to prosecution and two years' imprisonment if convicted.

That provision appeared to be aimed at such extreme right-wing white groups as the neofascist Afrikaner Weerstandsbeweging (AWB), or Afrikaner Resistance Movement. A senior government official said the AWB is being investigated under South Africa's Internal Security Act.

Under the broad language of the omnibus measure, the proposed cutoff of foreign donations could severely jeopardize the operations of such groups as the South African Council of Churches, which depends heavily on foreign contributions for its operating budget.

It also could effectively put out of business such benign policy study groups as the Cape Town-based Institute for Democratic Alternatives for South Africa (IDASA), which estimated today that 70 to 80 percent of its budget for devising models for a postapartheid South Africa comes from foreign funding.

The measure could also affect at least part of the $22 million that the U.S. government spends annually on various projects for black South Africans, including millions of dollars authorized by Congress to help scores of opposition groups fight apartheid.

A spokeswoman for the U.S. Embassy in Pretoria said, "It's a serious situation. We obviously are going to monitor it closely."

Additionally, funds spent by American labor to help start new black unions in South Africa could be affected, since the government views the black labor movement here as a political challenge to continued white-minority rule.

"What we are seeing in South Africa is the final transition to a totalitarian society," said IDASA coordinator Wayne Mitchell. "The government believes it is the vehicle for 'reform,' and anyone else who tries to play a role is seen as an enemy of the National Party."

The funding measure was introduced in Parliament by Justice Minister Kobie Coetsee, who likened donations from abroad to certain organizations to "petrol on a fire."

In a debate on a motion to create a special parliamentary committee to study the bill, Coetsee said that as long as foreign funds were coming in to some groups, there could never be a climate for reform. He conceded that existing law provides for the cutoff of foreign funds to groups declared to be "affected," but said the burden of proof was difficult to meet.

The new measure would empower Coetsee to declare groups or individuals who receive money from abroad to be "restricted," in which case the funds would be impounded by a "registrar of restricted organizations."

Funds proven to be earmarked for nonpolitical use would be released, while all other funds would either be returned to the foreign source or dealt with at the minister's discretion.