Officials of the Metropolitan Boston Arts Center yesterday disclosed tentative plans to offer the Group 20 Players "fair participation" in the MEBAC's new arts center on Soldiers Field Road.

The Wellesley summer theatre organization has protested against MEBAC's original plan to allow only the Cambridge Drama Festival to use the new site, which the Metropolitan District Commission plans to lease to MEBAC.

A spokesman for the Group 20 Players said last night he doubts that MEBAC intends to offer an "acceptable proposal" for sharing the theatre. "We feel that we should have equal time to use the site in the summer," he added.

MEBAC, which has already agreed to give the CDF full use of the theatre during the 1959 summer season, earlier suggested that the Wellesley group share the site in 1960, according to the Group 20 spokesman. He called this plan "no compromise, but an insult." Members of MEBAC "implied incorrectly that Group 20 is not in the same league with the Cambridge Drama Festival, professionally speaking," the spokesman continued.

Nelson W. Aldrich, vice-president of MEBAC, said yesterday that "if the Group 20 Players prove themselves capable of the quality of performance we require, we will certainly allow them to share the new theatre."

Mrs. John C. Vosoff, secretary of MEBAC, asserted that the organization is "doing everything possibue to be fair."