President P.W. Botha Friday extended the two-year nationwide state of emergency for another year and said ordinary laws were inadequate to control unrest.

His proclamation, which means hundreds of prominent activists will remain in jail without charge, was assailed by anti-apartheid leaders. White women from the Black Sash civil rights group stood along highways in Johannesburg during the morning rush hour with posters saying: "Apartheid is the emergency."The Rev. Frank Chikane, general secretary of the South African Council of Churches, said activists must "intensify our call for comprehensive economic sanctions against this apartheid regime."

Botha's announcement came two days after blacks ended their biggest and longest general strike against the white-controlled government. Black labor federations said about 1,000 workers who joined the protest have been fired.

The new emergency decree took effect immediately upon publication of a special government gazette in Pretoria. New press restrictions published in the gazette bar all media from quoting any member of an outlawed organization and require local news agencies to register with the government.

These domestic news agencies, many of them aggressive in their coverage of anti-apartheid activity, could be ordered to submit all their dispatches to a government censor before publication, the regulations say.

Journalists are already restricted in coverage of unrest, security force action, treatment of emergency detainees and a wide range of political statements the government considers subversive.

Another section gives the government power to extend the suspenions of two anti-apartheid newspapers, New Nation and South, which were closed down in recent months. New Nation's editor, Zwelakhe Sisulu, has been detained without charge since December 1986.

"It is indeed the aspiration of the government that conditions will change to such an extent that the declared state of emergency can be lifted," Botha said in a statement.

The emergency regulations allow sweeping powers of detention, outlaw many forms of peaceful anti-government protest and restrict freedom of speech, press and assembly.

Helen Suzman, long-serving member of Parliament for the anti-apartheid Progressive Federal Party, said Botha's announcement was "extremely depressing and hardly likely to restore confidence in the future stability of South Africa."

"We might just as well prepare ourselves for a permanent state of emergency," independent member of Parliament Jan van Eck told a gathering in Johannesburg on Thursday. "A minority regime will not be able to govern this country without the very wide and very arbitrary powers afforded by the state of emergency."

Under apartheid, South Africa's 26 million blacks have no vote in national affairs. The 5 million whites control the economy and maintain separate districts, schools and health services.

Despite banning of apartheid groups and restrictions on their leaders, more than 2 million blacks stayed away from work, school and shops from Monday to Wednesday. The strike was called to protest these restrictions and oppose labor legislation that could weaken black unions.

The action left streets deserted in major cities such as Johannesburg and Durban and cost the economy about $250 million, according to the Associated Chambers of Commerce.

Botha declared the nationwide emergency on June 12, 1986, after two years of daily violence that claimed 1,700 lives. By mid-1987, the violence lessened, although the toll had reached 2,500 from township political violence, anti-apartheid protests and security force action.

There have been about 100 bombings and land mine explosions in the country in the past two years.