The government said Saturday that President P.W. Botha met with Nelson Mandela last week, increasing speculation that the jailed black guerrilla leader will be freed before Botha leaves office in September.

The 45-minute meeting at Botha's official residence in Cape Town on Wednesday was the first time the two are known to have met.Government-run television reported that Foreign Minister Pik Botha "saw this as an event of the utmost contemporary importance." The television report quoted Pik Botha as saying the meeting had "positive implications which would benefit all people in South Africa."

However, Mandela's lawyer, Ismail Ayob, said, "I don't think it would mean anything like that unless a statement was made to that effect. I have no idea why the meeting took place. It could be Mr. Botha believes there is some benefit to him or the National Party or he may have wanted to hear Mr. Mandela's views."

Justice Minister Kobie Coetsee, who attended the meeting, said Mandela's "courtesy visit" was conducted in a "pleasant spirit."

Coetsee said no policy matters were debated and no negotiations were conducted but that the two men "availed themselves of the opportunity to confirm their support for peaceful development in South Africa."

The minister said the possibility of further meetings was not discussed.

Spokesmen for Coetsee would not say why the meeting had been kept secret. It was announced only after a reporter for the independent South African Press Association heard of the meeting and asked about it.

Unheard and unseen by the public since his conviction in 1964 on charges of plotting to overthrow the government, Mandela nevertheless has come to be the most admired leader among South African blacks, who consider him the embodiment of their quest for political freedom.

Mandela, who will be 71 on July 18, stays alone in a prison warden's house at the Victor Verster prison farm in Paarl, north of Cape Town. He is serving a life sentence.

Mandela has rejected the government's repeated offers to release him if he renounces violence. He has said the government should renounce violence against blacks, end apartheid and legalize the African National Congress, the largest guerrilla movement fighting the white-dominated government.

The ANC was outlawed in 1960, and the next year Mandela founded its guerrilla wing, Spear of the Nation. He was imprisoned in 1962 for leaving the country illegally and organizing an illegal strike by black workers. In 1964 he was convicted of sabotage and plotting the overthrow of the government and was sentenced to life in prison.

During the past year, Botha, 73, has dropped his requirement that Mandela renounce violence and has said he hopes it will be possible to free him. Botha is at odds with the governing National Party, whose leaders forced him to agree to retire from the presidency in favor of party head F.W. de Klerk. The change will occur after September parliamentary elections.

While many government leaders acknowledge the advantage of freeing Mandela and beginning negotiations with South Africa's black majority, they fear that such an action before an election could cause a black uprising and cost thousands of votes that would instead go to the right-wing.