VATICAN CITY (AP) _ Hundreds of Vatican lay employees pledged to donate part of their day's salary Monday to Pope John Paul II in a labor protest which a Vatican official denounced as ''completely unacceptable.''

Mario Cerullo, president of the Association of Lay Vatican Workers, said preliminary counts showed more than 90 percent of the 1,800 lay employees took part. The employees work at Vatican museums, the post office, main library, the daily newspaper L'Osservatore Romano, Vatican Radio and many offices.

Workers performed their jobs as usual but signed a special form promising to donate their first three hours' pay to the pope to help feed the poor, Cerullo said. He estimated donations would total about $40,000.

The labor action - called by the association an ''active strike'' - was called to protest plans to change the Vatican workers' pay schedule and to demand creation of a special office to resolve labor disputes in the world's smallest city-state.

''The Vatican employees want dignity and respect,'' Cerullo said in an interview. ''We hate to bother the Holy Father but we had to do something to show our unhappiness. I hope this is the first and last time.''

Archbishop Jan Schotte, a Belgian who handles labor relations for the Vatican, said in letters to Cerullo and Vatican-based cardinals that the protest was unjustified, extreme and ''completely unacceptable.''

He said salary and work conditions were ''superior to those existing in comparable work places'' and that negotiations could lead shortly to creation of a special labor office.

Cerullo said Vatican employees' salaries range from $927 a month to $1,370. The workers are exempt from Italian taxes, work a 36-hour week and have one month of vacation and 26 paid holidays.

The strike was triggered by the Vatican's recent decision to pay workers at the end of each month instead of at the beginning.