A spokesman for the Palestine Liberation Organization today affirmed that the PLO might be willing to accept United Nations Resolution 242, the basis upon which a Middle East peace conference could be held, if the wording of the resolution were changed to include "the legitimate rights of the Palestinians."

PLO spokesman Mahmoud Labadi categorized as "untrue" an earlier report that the PLO denied any willingness whatsoever to change its stand on Resolution 242. But he said in an interview today that it would be up to the U.N. Security Council to make the necessary amendment before the PLO could decide.

He also said that the PLO would regard acceptance of Resolution 242 as a basis for attending a Geneva conference to begin negotiations rather than as a formal recognation of Israel. However, if the United States and other interested parties were to interpret a PLO aceptance of Resolution 242 as a de facto recognition of Israel, "let them say it," he said. The policy of seeking to amend Resolution 242 was not new, Labadi said.

"We don't want to be an obstacle to peace. We want to be flexible but not at the expense of our legitimate rights to our homeland. We cannot go to Geneva showing all our cards. For us final recognition of Israel can only come out of a series of very long and difficult negotiations," Labadi said.

Yesterday both President Carter and a spokesman for Secretary of State Cyrus Vance said that they had been informed that the PLO would be willing to recognize Resolution 242 if the resolution could be changed to include the political rights of the Palestianians.

Resolution 242. passed in November of 1967, calls for an israeli withdrawal from occupied territories, peace within recognized and secure borders for all the states in the region and a just solution for Palestinian refugees.

Both Carter and Vance indicated that a PLO acceptance of Resolution 242 could be considered tantamount to a de facto recognition of Israel's right to exist. This is viewed here as a shift in American policy because Vance said in February that only a change in the Palestinian convenant would suffice to make the PLO eligible as a negotiating partner. When the PLO National Council met in Cairo the following month, however, it did not change the convenant or soften the PLO's stand on not recognizing Israel.

The attempt to get the Palestinians to accept Resolution 242 in order to bring the Palestinians to Geneva is seen here as an attempt to get around the problem of the Palestinian covenant which, in effect, calls for the end of the Jewish state.

In any case, Israel's Prime Minister Menhem Begin has already said he would veto any attempt to bring the PLO to Geneva no matter what it decided to do about Resolution 242. It is not yet clear that the United States would be willing to alter the wording of Resolution 242.

PLO spokesman Labadi called yesterday's development a "trial baloon" that the Americans sent up to test the reaction from all sides.

It is understood that PLO chief Yasser Arafat discussed the possibility of recognizing Resolution 242 in exvhange for a change in the wording with both the Saudi Arabians and the Egyptians last week. It is also understood that he discussed the possibility of a Palestinian government in exile as well.