August 7, 1985

The pressures for businesses to curtail links with South Africa because of that country's apartheid policy are expanding around the world, from Canada to Australia. Much of the pressure has focused on strengthening codes of conduct, such as the Sullivan Principles in the United States. Although the codes differ, typically they are voluntary, urging foreign companies in South Africa to treat black and white workers equally and to pay blacks a reasonable wage. But because it is felt that something stronger is needed, the debate increasingly is shifting to the possibility of sanctions. These measures, such as a ban on new investments in South Africa, have a far broader aim. Instead of trying to improve the conditions of the relatively few blacks working at foreign-owned factories there, they hope to achieve sweeping political and social change.

Carl C. Icahn and his group of investors have increased their stake in Trans World Airlines to 40.6 percent, or 13.9 million shares, the financier disclosed yesterday in a filing with the Securities and Exchange Commission. The higher stake, combined with the promise of major concessions from two of the carrier's three unions, gives the Icahn group a good chance to win control of the airline, analysts said. ''Icahn has got all the cards,'' Timothy Pettee, the airline analyst of L. F. Rothschild, Unterberg, Towbin, said. Mr. Icahn is competing against a $23-a-share offer by the Texas Air Corporation that T.W.A. has already accepted.

The space shuttle Challenger, which lost one of three main engines on its ascent to orbit eight days ago, returned safely to earth today after a mission that an official called ''superbly successful.'' Col. C. Gordon Fullerton of the Air Force guided the 108-ton spacecraft to a landing at 12:46 P.M. on a dry lake bed that danced with watery mirages in 96-degree heat. Plumes of dust rose like steam as the craft rolled to a stop, returning a crew of seven men and the largest, most advanced scientific instruments ever built for space flight. An Orbiting Observatory On this mission the Challenger became an orbiting astronomical observatory, with more than $72 million of telescopes and other sensitive instruments to study the sun, the stars and distant galaxies. Dr. Burton Edelson, an Associate Administrator of the National Aeronautics and Space Administration, said some instrument problems had seemed ''insurmountable when we started out.''

Seventeen representatives of the 21 active Arab League members were assembling here tonight for an emergency meeting, which was described by a senior Moroccan official as a last-chance effort to save the 40-year-old organization. The meeting on Wednesday, called by King Hassan II of Morocco to discuss ''issues dividing the Arabs'' and the ''Palestinian question in all its aspects,'' is being boycotted by Syria, Lebanon, Southern Yemen and Algeria. Only 8 Leaders Are Expected The meeting was to have brought together all Arab League heads of state. But only eight leaders are expected to be present Wednesday, along with the chairman of the Palestine Liberation Organization.

International South African police raided the home of Winnie Mandela, an anti-apartheid leader, after firing rubber bullets and using whips to break up a demonstration outside. Lawyers for Mrs. Mandela, who is the wife of the jailed nationalist leader Nelson Mandela, said an infant grandchild had disappeared after the raid. [Page A1, Column 1.] 17 Arab countries are represented at a meeting today in Casablana of the 21 active members of the Arab League. The meeting is being boycotted by Syria, Lebanon, Southern Yemen and Algeria. [A1:3.] Forbes Burnham died in a Guyanese hospital after a throat operation at the age of 62. He had ruled Guyana since 1964. [A9:1-3.] National The shuttle Challenger landed safely at Edwards Air Force Base, Calif. The spacecraft lost a main engine after liftoff, but an official said the eight-day mission had otherwise been ''superbly successful.'' [A1:6.] A baseball strike began as 650 players stayed away from major league parks and forced the cancellation of 13 games. Negotiators held their longest bargaining meetings of the nine months of talks, but no significant progress was reported in efforts to reach a new collective-bargaining accord. The last baseball strike, in 1981, lasted 50 days. [A1:4.] Widespread student loan defaults totaling $4.1 billion have prompted the Education Department to ask the Internal Revenue Service to withhold income tax refunds for a million people who defaulted on the loans unless they begin paying their debts.