The nation's Roman Catholic bishops yesterday warned that Catholics may not dissent from the church's teachings on abortion and may not support those who dissent.

A spokesman for the bishops' Office of Pro-Life Activities here said the statement on dissent was aimed at a group of Catholic academics, priests and nuns who signed a controversial newspaper advertisement during last year's presidential election campaign asserting that there is "a diversity of opinion" about abortion among faithful Catholics.

The full-page ad in The New York Times ran last October at the height of the dispute between Cardinal John J. O'Connor, archbishop of New York, and Catholic political figures over the obligation of Catholic officeholders to support legislation favored by their church.

The Vatican ordered 24 nuns who were among the nearly 100 signers of the ad to recant or face possible expulsion from their orders. Two of the 24 have said they have "resolved" their dispute with the Vatican; the other cases are pending.

In his capacity as head of the bishops' Pro-Life committee, Cardinal Joseph L. Bernardin, archbishop of Chicago, said that "the church's teaching on abortion is binding" on all Catholics.

"A Catholic who chooses to dissent from this teaching, or to support dissent from it, is dissenting not only from church law but from a higher law which the church seeks to observe and teach," he said in the statement, which was approved last month by the administrative committee of the National Conference of Catholic Bishops.

Bernardin, a liberal prelate who was responsible for the Catholic bishops' 1983 pastoral letter condemning nuclear warfare, stitched war, abortion and economic injustice -- the subject of a pastoral letter currently in process -- together into a "seamless garment" of concern for life.

He denied that the church's position on abortion threatened women's rights. "We . . . stand with the child who has no voice of his or her own, and we also stand with the woman facing problems in pregnancy, doing all we can to provide her with effective, morally acceptable assistance," he said.

In recent weeks, sponsors of the original ad in support of "diversity of opinion" on abortion have been soliciting signatures and financial support for a second one affirming "solidarity with all Catholics whose right to free speech is under attack." In the wake of criticism from a number of sources, plans for the second ad have been temporarily shelved, said Frances Kissling of Catholics for a Free Choice. Last week, the independent National Catholic Reporter, a liberal Catholic weekly, editorially warned readers against signing the second ad, which it said would "cause more conflict and further inhibit meaningful dialogue."

Kissling, whose Catholics for a Free Choice was a substantial target for yesterday's statement, said the dissent registered by her group "is well within the traditional definition of legitimate dissent . . . theologically and ethically defensible."