JOHANNESBURG, JUNE 4 -- Black South African leader Nelson Mandela expressed the hope that his country's four-year state of emergency is about to be lifted as he left here today on a six-week international tour in which he said the issue of sanctions against the white-led government "is going to be uppermost in all the discussions."

Mandela will visit 13 countries, including 10 days in the United States during which he will visit several cities, be given a ticker-tape welcome in New York, address Congress and meet President Bush on June 25.

Looking fit despite surgery for a bladder cyst last week, the 71-year-old black leader, who was freed in February after nearly 28 years in prison, said he was looking forward particularly to his U.S. visit, "to thank the American people for the important role they have played in the fight against apartheid."

"The United States is the only country which has incorporated a measure in its legislation making it an offense to trade with South Africa," said Mandela, who is deputy president of the African National Congress, South Africa's main black political movement.

Within hours of leaving the hospital Saturday, Mandela held an unannounced meeting with President Frederik W. de Klerk, and today he sounded optimistic that the state of emergency is about to be lifted -- adding to speculation that de Klerk plans to scrap or modify it within a week.

"It was part of the Groote Schuur agreement that the state of emergency should be lifted, and I hope this will now be done," Mandela told reporters at the airport, referring to talks last month between the ANC and the government at the president's official residence in Cape Town to resolve obstacles in the way of negotiations for a new national constitution.

Details of what was agreed at those ground-breaking talks have not been fully disclosed, but Jacob Zuma, an ANC member of a joint committee appointed to hammer out details, confirmed today that scrapping the emergency was part of the deal.

"I think the whole state of emergency will be lifted this week," Zuma said before boarding the plane to accompany Mandela on the first leg of his tour, to neighboring Botswana.

Afrikaans-language newspapers close to the government also speculated today that the emergency, which is due for renewal June 12, would be allowed to lapse, although they suggested it might be retained in Natal Province, where fighting between rival black groups has become widespread.

However, Mandela stressed in response to reporters' questions at the airport that even if the emergency is lifted, thus meeting one of the ANC's major conditions for entering into negotiations with the government, it would not change his decision to urge leaders he meets on his tour to continue sanctions against South Africa.

"The question of sanctions is going to be uppermost in all the discussions," he said.

De Klerk is said to be hoping that another burst of changes will persuade Western leaders to reward him by lifting or easing sanctions, but Mandela takes the view that international pressures must be maintained to force the government to negotiate a democratic, non-racial constitution rather than a modified version of apartheid.

Among countries Mandela will visit on his tour are West Germany, Britain, France, Italy, Switzerland, Belgium, Ireland and Canada. He will address the European Community and European Parliament in Strasbourg June 13 and 14, and meet with Pope John Paul II.

Mandela is scheduled to return briefly to South Africa June 18, for his 72nd birthday.

The flurry of concern about Mandela's health last week when he entered a clinic for a minor operation underscored the extent to which he is now recognized by white and black South Africans alike as crucial to the delicate negotiating process underway.

When the newly established ANC headquarters here failed to disclose the nature of the surgery, rumors spread that Mandela, who had a prostate operation in prison, might have cancer. But on Saturday, Mandela held a press conference as he was leaving the hospital and his surgeon, Louis Gecelter, said he had removed a bladder cyst that laboratory tests had shown to be nonmalignant.

"There should be no problems or aftereffects," Gecelter said. "Mr. Mandela is a very fit young man for his age."

In a new outbreak of violence today, police opened fire with shotguns, rubber bullets and tear-gas grenades on a crowd of blacks who threw stones at municipal workers bulldozing their squatter settlement near Alberton, east of Johannesburg. At least 20 people were reported injured.

It was the first time in many months that the authorities have attempted the forced removal of a black community, a policy that was once a major cause of racial conflict in South Africa.