South African security forces killed 10 alleged insurgents of the outlawed African National Congress in two separate gun battles during the past two days, the government announced today.

The deaths bring to 32 the number of suspected ANC operatives killed or captured since the underground resistance movement intensified its campaign of assassination, sabotage and urban bombs following Pretoria's imposition of a nationwide state of emergency. Altogether 131 people have died since the June 12 declaration.

Meanwhile, Winnie Mandela, wife of imprisoned congress leader Nelson Mandela, confirmed that her husband would refuse to meet with British Foreign Secretary Geoffrey Howe during his planned diplomatic mission to South Africa in two weeks. Her statement, which came after visiting her husband in prison in Cape Town, means all of the country's leading antiapartheid activists will be boycotting Howe during his visit.

The first gun battle occurred yesterday morning, according to police, who said they confronted seven men in the Alldays district about 30 miles from the Botswana border in the northern Transvaal, scene of several explosions from land mines planted by ANC operatives in recent months.

Six of the men were shot dead after what police described as "a fierce gun battle," and a seventh man, who may have been wounded, escaped. One policeman was also reportedly wounded.

None of the dead was identified, although police described them as "trained ANC terrorists" believed to have crossed the border from Botswana. Police also said they seized a large quantity of Soviet-made weaponry, including limpet mines, hand grenades, automatic rifles and pistols and ammunition.

Limpet mines have been used in several terrorist bombings at a bus stop, restaurant, hotel and supermarket in recent weeks in Johannesburg and Pretoria. The ANC, which is based in Lusaka, Zambia, has neither asserted responsibility for these attacks nor denied that they may have been carried out by its operatives inside South Africa.

The second gun battle took place at around 8:15 this morning near King Williams Town in the eastern Cape region, a stronghold of antigovernment resistance. Police said they stopped a car after a tip-off and that the four occupants got out and opened fire. One allegedly threw a hand grenade that did not detonate.

Police returned the fire, killing one man, they said. The other three raced off but their car was trapped a few miles away and two jumped out and fled down an embankment into nearby bushes. Both were shot dead there.

The fourth man, who police said had apparently been wounded earlier, was found dead in the vehicle.

Police said they had identified one of the four as a trained ANC agent and the other three were presumably agents or accomplices. Hand grenades and Soviet-made pistols and automatic rifles were confiscated from the car.

There was no independent confirmation of the police account, released by the state Bureau for Information. Under the sweeping emergency censorship restrictions that govern the filing of this report, the bureau is the only authorized source of news on police activities.

The government said it had killed 17 suspected ANC agents since the emergency began, including three killed in a shoot-out Monday north of Durban and two killed early Saturday morning who reportedly were participating in a hit squad raid on black township police in two townships east of Johannesburg. They reportedly used automatic weapons similar to those captured today.

The bureau also reported two other deaths in recent days in fighting between black residents in the Meadowlands area of Soweto and nearby hostel dwellers.

Despite the 12 new deaths, a bureau official claimed there had been a 23 percent drop in incidents of civil unrest this past week and a 77 percent decrease since the emergency was declared. But he refused to reveal the number of unrest incidents and there was no way to independently verify his claims because of the government's ban on journalists entering unrest areas and reporting on such incidents.

Two buildings used by antigovernment activists were set ablaze in Johannesburg early this morning. A fire, allegedly started by arsonists, gutted the offices of several black trade unions in a building in downtown Johannesburg.

Three firebombs were later thrown at a house in Berea neighborhood where members of the country's anticonscription campaign live. There were no reported injuries.

Police also announced new emergency restrictions on five areas in KwaZulu, the black "homeland" in northern Natal. Nonresidents are prohibited from entering the area and the movement of students and other residents around school areas is restricted. The order also bans T-shirts and other clothing bearing the names of 12 antiapartheid organizations, including the United Democratic Front and the Congress of South African Trade Unions.

In another development, the government has ordered an American Lutheran missionary couple from Lynnwood, Wash., to leave the country by next week, one of the missionaries said Friday. The Revs. Brian and Susan Burchfield, who have been helping a Cape Town pastor with his 600 mixed-race parishoners since January, were notified in a letter from the Home Affairs Ministry last night, Susan Burchfield told The Associated Press. She said no reason was given.

In rejecting a meeting with British Foreign Secretary Howe, Winnie Mandela said her husband saw no point in meeting yet "another eminent person," referring to the Commonwealth Eminent Persons Group whose diplomatic mission here ended in failure in May after the government pulled back from negotiations with the ANC.

Anglican Bishop Desmond Tutu and the Rev. Allan Boesak of the Dutch Reformed church also have refused to meet with Howe, to protest his and Prime Minister Margaret Thatcher's opposition to economic sanctions against South Africa.