August 21, 1982

President Reagan, saying that an agreement had been reached to end the crisis in west Beirut, ordered about 800 marines today to participate in a three-nation force to insure the safe evacuation of Palestinian and Syrian fighters from the city. In his televised statement from the White House, Mr. Reagan said the successful carrying out of the two-week phased evacuation, which is to begin Saturday, would ''set the stage'' for the rapid departure of all foreign troops -Israeli, Syrian and Palestinian - from the rest of Lebanon and for the restoration of Lebanese control over the country. He said it would also help to safeguard northern Israel from attacks from Lebanon. ''We must also move quickly in the context of Camp David,'' the President said, ''to resolve the Palestinian issue in all its aspects, as well as the other unresolved problems in the Arab-Israeli conflict. Only when all these steps are accomplished can true and lasting peace and security be achieved in the Middle East.''

The Palestine Liberation Organization returned two captured Israelis Friday, the first step in an American-negotiated plan to withdraw Palestinian guerrillas from besieged west Beirut. The Israelis, a pilot shot down on the first day of the invasion and a soldier taken from his observation post Wednesday night, were carried in a Red Cross caravan across the port of Beirut to Israeli troops in the Christian eastern section of the capital. French Foreign Legion paratroops, the first contingent of a multinational peacekeeping force that is to supervise the pullout, landed at the port at dawn today. (The French force found no sign of the Lebanese Army troops who were supposed to have taken control of the port from Israeli and Palestinian forces, according to an Associated Press report. French officers traded harsh words with their Israeli and Lebanese counterparts as the deployment got under way, with French soldiers marching to take over Israeli positions in the port area.)

A senior State Department official suggested today that the introduction of more weapons to Central America be limited and that the numbers of foreign military advisers in the region be reduced to zero. The official, Thomas O. Enders, Assistant Secretary of State for Inter-American Affairs, indicated that such steps should be part of renewed and greater efforts to achieve peaceful solutions to civil and regional conflicts in Central America. In tone and emphasis his speech to the Commonwealth Club in San Francisco seemed to be less confrontational than statements on Central American policy made soon after the Reagan Administration took office in early 1981. 'Cornerstones of Peace' Mr. Enders urged the left-wing Government of Nicaragua to discuss ways of easing tensions, saying, ''The cornerstones of peace are there.''

The stock market continued to surge yesterday, capping an exhilarating week in which both prices and trading volume reach record levels. The Dow Jones industrial average climbed a further 30.72 points, finishing the trading session at 869.26. For the week, the blue-chip average was up 81.24 points. Trading volume for the day was 95.9 million shares, bringing the week's volume on the New York Stock Exchange to 455.1 million shares.

The Soviet Union has accepted President Reagan's offer of a one-year extension of a grain sales agreement due to expire Sept. 30, Agriculture Secretary John R. Block announced today. The acceptance was delivered in writing today to the American Embassy in Moscow, Mr. Block said. He added in a statement that ''the willingness of the Soviet Union to accept this extension is proof that the Soviets believe the President's pledge that the United States will again be a reliable supplier.'' That statement was in contrast to the acrimony that has surrounded President Reagan's ban on the use of American-made or Americanlicensed equipment for the construction of a 3,700-mile pipeline to bring natural gas from Siberia to the Soviet Union.