Officials with the Civil Liberties Union of Massachusetts (CLUM) said yesterday that they are investigating whether a lease agreement between the Cambridge Public School District and the Catholic Archdiocese of Boston breaches laws mandating the separation of church and state.

The city currently leases three abandoned church schools for use as temporary classrooms. But some city residents have objected to the use of two of the buildings, because large crucifixes erected atop their roofs remain in place.

CLUM attorneys believe the religious symbols may violate the First Amendment and the constitution of the Commonwealth of Massachusetts, according to John Reinstein, the group's legal director.

"We are pursuing an investigation into all aspects of the use of church buildings as temporary sites of the Cambridge public schools," Reinstein said in an interview with The Crimson.

About 540 students are attending the temporary school sites at Notre Dame de Pity Church in North Cambridge and the Patronage of St. Joseph in Union Square, said James R. Ball, public relations agent for the Cambridge school district.

The district is using the sites while it awaits the September 1995 reopening of Agassiz and Haggerty Schools, which were originally built around 1900 and demolished in 1993 because of structural damages, Ball said.

"The Catholic Church is really helping us out," said School Committee member Alfred B. Fantini. "If not for their facilities, we'd have no place to put our children."

According to Fantini, the former Catholic school sites were chosen after a public bidding process. The archdiocese offered the lowest rental fees, and best fulfilled the district's needs, he said.

"There are not many options open to us without them," Ball said. "We would be forced to split up children, use split shifts or purchase portable classrooms."

Father Richard J. Brady, pastor of St. Joseph's, said the archdiocese has shown sensitivity by removing all religious icons and inscriptions from the building's interior.

"[B]ut we're certainly not going to knock down a cross that's been there since the place was built," Brady said.

Francis S. Cohen, general counsel to the CLUM,said the crucifix amounts to an unconstitutionalendorsement of religion by the school district.

"It would make certain students feel likeoutsiders," Cohen said. "It needs to be lookedinto."

Reinstein said his office has been contacted byconcerned parents of several children attendingthe schools.

Eric T. Chester, a 51-year-old Arlingtonresident whose son Jeffrey, 12, attends thetemporary school at St. Joseph's, said the schooldistrict and the city of Cambridge have"Repeatedly" been insensitive to non-Christians.

Chester said he has asked Eva Paddock, theschool's principal, to consider removing thecrucifix, but that Paddock has offered noresponse.