Salvadoran guerrillas have demanded the release of 34 prisoners as part of their conditions for freeing the kidnaped daughter of President Jose Napoleon Duarte, according to Salvadoran sources close to the leftist rebels.

The list reportedly includes Nidia Diaz -- a leader of the Central American Revolutionary Workers' Party held responsible for the June 19 killing of 13 persons, including four U.S. marines -- and Julio Romero Talavera, a Costa Rican pilot of an arms-laden plane that crashed here in 1981.

Red Cross officials were seen at Mariona Prison, reportedly to check on the health, judicial status and location of the listed people. There were reports that some names are unknown to the government, which is not known to have agreed to the terms.

Other Salvadoran sources said the Pedro Pablo Castillo Front, which has claimed responsibility for the Sept. 10 kidnaping in secret radio communications with Duarte, appears to be a special "SWAT team" allegedly set up by the five guerrilla organizations to carry out the kidnaping. Such a finding would explain why the guerrillas' political wing and middle-level leaders have denied knowledge of the kidnaping.

Gunmen kidnaped Ines Guadalupe Duarte, 35, and her friend Ana Cecilia Villeda, 23, on Sept. 10 as they arrived for class at a local college.