Twenty-seven Harvard professors today called for an investigation into the recent killings of Palestinian refugees in West Beirut camps in a paid advertisement in The Crimson.

The ad, also signed by four other area professors, denounces the killings as a "barbarous atrocity" and demands the resignations of Israeli Prime Minister Menachem Begin and Defense Minister Ariel Sharon if they had any previous knowledge of the massacres.

A new student organization, Harvard Jews for Peace and Justice, collected the signatures and purchased the ad.

The statement, which appears on page 8, also warns Israel that "further intransigence" could jeopardize Middle Eastern peace. It endorses President Reagan's peace plan for the region.

Signers of the ad include Henry Rosovsky, dean of the Faculty: Stanley Huffmann, Dillon Professor of the History of France, and Zvi Griliches, chairman of the Economics Department.