Warsaw GhettoWARSAW, April 18 (AP).-Representatives of Jewish organizations in twenty countries joined the central committee of Polish Jews today in honoring the memory of 500,000 Jews who perished in the Warsaw ghetto during the Nazi occupation.

The committee opened formally the National Museum of Jewish Martyrology in memory of the Jews who fought the Germans in the ghetto revolt of 1943 and the subsequent general Warsaw insurrection. Dr. Adolf Berman, committee president, led the program.