Secretary of State Warren Christopher, on a five-country tour of Latin America, has initialed an agreement opening the way for Brazil to purchase nuclear technology from American companies.

Secretary Powell arrived here today for a short visit before heading to Beijing for the most important stop on his five-country tour of the region.

President Clinton is traveling again, scheduled to leave on a five-country African tour at 5:40 P.M. on March 22 and to return on April 2, around dinnertime.

The five-country tour was designed to show support for neighboring Azerbaijan, which is ethnically close to Turkey, in its conflict with Armenia.

But the Ayatollah pressed ahead today with long-scheduled plans to meet with Mr. Shevardnadze, who is winding up a five-country Middle East tour.

Mr. Bush, who will hold talks with Mr. Mbeki on Wednesday as part of a five-country tour of Africa, has called for a change of leadership in Zimbabwe.

Treasury Secretary John W. Snow, speaking here Thursday at the end of a five-country European tour, said the United States opposed "heavy-handed" curbs on markets.

One way was to match the Graham company with the Chase Manhattan Bank, which is sponsoring a five-country Asian tour in October and November.

Secretary Powell had returned to Vietnam as part of a five-country tour of the region, to attend the annual foreign ministers' conference of the Association of Southeast Asian Nations.

On a five-country tour of the Middle East, Carter visited Damascus on March 14-15, 1990, and held talks with Assad.