ROME - The Vatican issued guidelines for Roman Catholic politicians yesterday that underlined the church's opposition to abortion, euthanasia and same-sex marriages and told Catholics not to promote laws that favor those practices.

While the church positions in the guidelines are not new, the guidelines seek to remind Catholics of what the Vatican cast as their duty at a time when legislation in many countries has moved in directions displeasing to many church officials.

"Those who are directly involved in lawmaking bodies have a grave and clear obligation to oppose any law that attacks human life," say the guidelines, written and published by the Vatican Congregation for the Doctrine of the Faith.

"For them, as for every Catholic, it is impossible to promote such laws or to vote for them," the guidelines continued.

Those instructions came in a passage of the document that refers explicitly to abortion and euthanasia but that also seems to be rendered broadly enough to encompass issues such as human cloning and research using embryonic stem cells.

The guidelines, translated by the Vatican into six languages, say that "laws must defend the basic right to life from conception to natural death."

"In the same way" they add, "it is necessary to recall the duty to respect and protect the rights of the human embryo."

"Although we don't mention cloning or stem-cell research ... these developments will pose challenges for Catholics," said the Rev. Augustine Di Noia, undersecretary for the Congregation for the Doctrine of the Faith.

The document was approved by Pope John Paul II and signed by Cardinal Joseph Ratzinger, head of the congregation.