April 23, 1986

In a sharp break with the euphoria that has sent interest rates sharply lower in the last few months, prices of Treasury bonds fell nearly three points yesterday as yields rose sharply in active and hectic trading. By the end of New York trading, the bellwether 9 1/4 percent Treasury bonds due in 2016 were offered at 123 1/8 to yield 7.36 percent, up from 7.15 percent a day earlier and 7.10 percent April 16. The 9 1/4 percent issue fluctuated erratically during the day between an early morning high of 126 and an afternoon low of about 122 5/8. Rates on Treasury bills also increased by a tenth of a percentage point or more, with the six-month issue rising to 6.03 percent from 5.87 percent at Monday's auction.

Britain said today that it planned to expel 21 Libyan students for suspected involvement in ''student revolutionary activities.'' The 21, all of whom were arrested today, included a pilot trainee who authorities say telephoned Tripoli radio last month with an offer to form suicide squads to bomb United States military targets. The expulsions of the Libyan students were ordered by the Home Secretary ''in the national interest.'' Statement by Home Secretary British authorities said the 21 students, all men, had been under surveillance for some time, and today Douglas Hurd, the Home Secretary, said all had been actively involved in organizing Libyan student activities in Britain to support the Government of Col. Muammar el-Qaddafi. ''What we have done is not in any way vindictive or persecuting anyone,'' Mr. Hurd told the House of Commons. ''It is a clear sign that we are determined to get rid of troublemakers.'' [ In Washington, officials said the Reagan Administration was tightening surveillance of Libyans living in the United States. The officials said the step was taken after the Administration decided against a proposal to deport the Libyans, who are thought to number 3,500. Page A4. [ In Paris, French officials, confirming a statement by President Reagan, said the Government had favored a more ambitious and hard-hitting raid against Libya than the one carried out by the United States.

The President of Austria said tonight that documents about Kurt Waldheim's wartime activities showed that he must have been aware of German reprisals against partisans in the Balkans. But the President, Rudolf Kirchschlager, said the documents offered no substantiation for other charges, such as that Mr. Waldheim took part in war crimes or knew about the deportation of Greek Jews to Nazi death camps. The documents were made available by the United Nations and the World Jewish Congress. Two Weeks Before Election The President's report was delivered in a broadcast address less than two weeks before a presidential election in which Mr. Waldheim, the former United Nations Secretary General, is favored to succeed Mr. Kirchschlager.

THERE have been ghost writers, but there has not been a ghost cook - until now. Martin Rapp, a director of the Traveller's Bookstore at Rockefeller Center, is a man who adapts, improvises and occasionally invents dishes and cooks them for friends who are restaurateurs, caterers and food writers. Yet he receives neither remuneration nor credit for his efforts or recipes. He is also a man whose close friends call him and say that they will give a dinner party - if he will cook. When Anstice Carroll, food director of Grace Church School, caterer and Mr. Rapp's friend of 20 years, proposed a menu for a show of Australian art at Public School 1, he suggested his lobster strudel recipe. When she got the job, he took a day off to help make 35 strudels. When the Italian restaurant Wise Maria opened in SoHo, Mr. Rapp, finding its desserts uninspired and inauthentic, offered a chocolate cake that originated in Capri. The owners, and a subsequent restaurant reviewer, loved it.

The chief executive of the International Business Machines Corporation, John F. Akers, says the company is growing ''increasingly discouraged'' about its ability to continue business operations in South Africa. Mr. Akers also said for the first time that I.B.M. is ''constantly reviewing'' whether it should close down its South African subsidiary. ''The economic activity there is worse than it was a year ago, the economic pressure in the United States is heightened, and Mr. Botha is too slow,'' Mr. Akers said in an interview Monday, referring to P. W. Botha, the president of the white minority Government. ''If we cannot have as successful a business remaining in South Africa as we would have leaving, then I think we have no choice than to leave.''