Pope John Paul called euthanasia a distortion of medical ethics on Friday, saying doctors should not decide “who can live and who must die.”

But while condemning euthanasia, the Pope said terminally ill patients have the right to refuse medicine and therapy that prolongs their lives artificially without hope of recovery.

The Pope’s words, read in a major address to Catholic health workers attending a Vatican conference, come at a time when several countries are debating euthanasia laws.

“Euthanasia is among the dramas of an ethic that presumes to establish who can live and who must die,” the leader of the world’s some 1 billion Roman Catholics said.

The Pope, who has Parkinson’s disease, said even if euthanasia is sometimes motivated by “badly understood” compassion or an attempt to preserve human dignity, it is morally unacceptable because it suppresses human life.

Euthanasia was an issue in the U.S. presidential debate and a number of countries in Europe are preparing legislation to regulate it.

The Catholic Church teaches that life begins at the moment of conception and ends at the moment of natural death.

“Compassion, when devoid of the willingness to confront suffering and stand by those who are suffering, puts an end to life where it aims to end pain, thus distorting the ethical statutes of medical science,” he said.

Euthanasia is permitted in some European countries such as Switzerland, the Netherlands and Belgium. Belgian lawmakers want to expand its legislation to include children and teenagers.

Spain’s Roman Catholic Church has launched a campaign against euthanasia in an attempt to pre-empt any move by the country’s new Socialist government to legalize it.

In Britain, where a parliamentary inquiry has begun on liberalizing rules on euthanasia, a recent survey by a pro-euthanasia group said 47 percent of 790 people questioned would risk jail if a loved one asked them for help to die.

In his address, the Pope restated the Church’s position that the terminally ill have a right to refuse what some have called “obstinate therapy” - continuing to give medicine even when there is no hope of recovery.

“The refusal to receive obstinate therapy is not a refusal by the patient of his life,” the Pope said, adding it was “ethically correct” to stop treatment if the result was “clearly inefficient or disproportionate.”

France is looking to change its laws, without legalizing the taking of life, to allow patients and their families to choose to end treatments that simply delay death.