A top Vatican (search) cardinal said Friday that priests must deny communion to pro-abortion Catholic politicians (search), but he would not comment on whether it was right for John Kerry (search) to receive communion.

Cardinal Francis Arinze spoke at a news conference to launch a new Vatican directive clamping down on liturgical abuses in Mass which bars lay people from giving sermons, non-Catholics from taking communion and rites of other religions from being introduced in the service.

The document restated church teaching that anyone who knows he is in "grave sin" must go to confession before taking communion.

Arinze was asked whether that meant that Kerry should not request or be given communion for his unapologetic support of human rights, including a woman's right to abortion.

The Democratic presidential candidate says he personally opposes abortion, but supports the rights of others to have one. He argues that church doctrine allows Catholics the freedom of conscience to choose.

Arinze, a Nigerian whose Congregation for Divine Worship and the Discipline of the Sacraments issued the document, said the church's position was clear and that U.S. bishops should decide.

When pressed to speak generally about the case of "unambiguously pro-abortion" Catholic politicians, Arinze concurred that such a politician "is not fit" to receive communion.

"If they should not receive, then they should not be given," he said.

Bishop Raymond Burke, the archbishop of St. Louis, has said he would refuse to give Kerry communion; Kerry's own archbishop, Sean O'Malley of Boston, has endorsed that principle without naming the senator.

The Vatican directive, commissioned by Pope John Paul II, softened a stricter earlier draft that had discouraged the use of altar girls and denounced such practices as applauding and dancing during Mass.

It said, however, that "shadows are not lacking" and that the Vatican cannot remain silent about abuses that "not infrequently plague liturgical celebrations."

And it reiterated the pope's view that the "mystery of the Eucharist is to great for anyone to treat it according to his own whim."

Roman Catholics believe that they receive the body and blood of Christ when they take communion.

The Second Vatican Council in the 1960s led to many liberalizing changes in the Mass, such as having priests face the congregation and celebrating the service in the local language rather than Latin.

The 71-page document, called an instruction, keyed on what the Vatican considers such abuses as lay people increasingly taking on the role of priests, even non-Christians "out of ignorance" coming forward to take communion and the introduction into the Mass of books and rites of other religions.

The document said only priests may read the Gospel to congregations, and that only priests or deacons may deliver the homily — never lay people. However, it allowed that bishops can appoint "extraordinary ministers" to give communion when there is no priest available.

It said the use of altar boys was "laudable" but repeated Church policy that girls or women may also serve at the altar.

The document made no specific mention of clapping or ritual dancing during Mass, as the pope himself has witnessed during his trips to Africa and elsewhere.