INDIANAPOLIS (AP) _ The Rev. James E. Andrews of Atlanta was installed today as stated clerk of the Presbyterian Church (USA), the church's highest administrative office.

Andrews, 57, was elected at last year's Presbyterian General Assembly in Phoenix, Ariz., and his installation today marked the first business of the first full day of the 197th Assembly, which opened Tuesday night.

Andrews was leader of the church's Southern branch for 10 years, until the Southern and Northern branches united in 1983 after being separated since the Civil War. Two years ago, he became co-stated clerk of the reunited Presbyterian Church.

The assembly also was scheduled today to elect a moderator, who will serve as leader of the assembly and serve as an ambassador to Presbyterian churches and missions around the world.

Abortion is expected to be one of the most controversial issues facing the 600 voting delegates at the assembly.

On Thursday, 21 petitions from Presbyterian groups across the country are expected to be heard by the church's Committee on the Justice and Rights of Persons.

The majority of the petitions will likely represent a challenge to the church's pro-choice stand on the issue of abortion, a position held by the church since 1970, delegates said.

Church leaders also will confront such issues as Central American politics and homosexuality during the nine-day annual conference.

About 5,000 Presbyterians were expected to attend the assembly at the Indiana Convention Center. The assembly reviews the work of the past year and formulates new policy for the 3.1-million-member church, officials said.