Johannesburg — South Africa's main white opposition party, the Progressive Federal Party, has decided to defy the government and open its membership to all races. The Progressive Federal Party's action is one more blow against a law passed in 1968 banning mixed-race political parties in South Africa. Many political analysts suggest the law has become untenable and will be scrapped or overhauled by the government during the 1985 parliamentary session.
Open political parties would not necessarily upset the political balance in South Africa, since blacks cannot vote and whites outnumber the Colored (persons of mixed race) and Indian groups, which were given some limited representation in Parliament this year.
But a change or end to the so-called Prohibition of Political Interference Act might be evidence that South Africa's new Constitution, which brought Coloreds and Indians into new separate chambers of Parliament this year, has generated some pressure for political changes not envisioned or desired by the government.
It was the Colored Labor Party that first refused to abide by the law during Colored and Indian elections to Parliament earlier this year. Certain Indians ran for election to the Indian chamber of Parliament as independents, though it was clear to everyone that they were active supporters of the Labor Party.
The government has agreed to look closer at the law next year. A reaffirmation of the segregationist law could force the Labor Party to withdraw from the new Parliament - something the government undoubtably will try to avoid at almost any cost.
Veteran Progressive Federal Party member Helen Suzman said she was ''delighted'' with her party's decision to ignore the ban on integrated political parties. She is convinced pressure is building on the government to such an extent that ''the law will have to be dropped.''
When the Prohibition of Political Interference Act was passed in 1968, it caused the Liberal Party, one of whose founders was well-known writer Alan Paton , to disband since it had a multiracial membership. The Progressive Federal Party, then just called the Progressive Party, decided to stay in existence and suspend the membership of nonwhites.
Since 1968 the Progs, as party members are called, have become the official opposition in the white Parliament. Although the Progressive Federal Party has always opposed the forced segregation of political parties, it has not openly defied the law.
In explaining the action taken over the weekend by the party's federal council, Prog chairman Alex Boraine said the party would not actively recruit black, Colored, or Indian members, but it would accept their membership applications.
Mr. Boraine said he did not expect any great numbers of nonwhites to join the party now. But he felt the party's stance in opposition to the law was important as a sign of the nonracial society that party members think South Africa should become.
It would be ironic if South Africa's new Constitution should eventually force the scrapping of the Prohibition of Political Interference Act, since the new Constitution is an outgrowth of strict political segregation.
The Constitution calls for separate parliamentary chambers for whites, Indians, and Coloreds and for each to legislate separately on matters affecting each group.