Pope Francis, whom conservatives in the Roman Catholic Church have accused of not speaking out forcefully enough against abortion, on Monday called the practice "horrific."

Unfortunately, what is thrown away is not only food and dispensable objects, but often human beings themselves, who are discarded as unnecessary. - Pope Francis

The pope made his toughest remarks to date on abortion in his yearly address to diplomats accredited to the Vatican, a speech known as his "State of the World" address.

"It is horrific even to think that there are children, victims of abortion, who will never see the light of day," he said in a section of the speech about the rights of children around the world.

Abortion, he said, was part of a "throwaway culture" that had enveloped many parts of the world.

"Unfortunately, what is thrown away is not only food and dispensable objects, but often human beings themselves, who are discarded as unnecessary," he said.

Since his election in March, the pope, while showing no signs of changing the Church's position against abortion, has not spoken out against it as sternly or as repeatedly as his predecessors Pope Benedict XVI and the late John Paul II.

Both of those popes often delivered sermons against abortion, which the Church considers murder.

Conservatives in the Church were alarmed when Francis, in a landmark interview in September with the Italian Jesuit magazine Civilta Cattolica, said the Church must shake off an "obsession" with teachings on abortion, contraception and homosexuality.

His stance favouring mercy over condemnation has disoriented conservative Catholics, notably in rich countries such as the United States, where the Catholic Church has become polarized on issues such as abortion.

Last year, Bishop Thomas J. Tobin of Providence, R.I., spoke for many conservative Catholics when he said he was disappointed that the pope had not addressed "the evil of abortion" more directly.

Conservative Catholic websites have criticized the pope in the past months for what they called his silence on abortion.

In the part of his speech about children, Francis also deplored their use as "soldiers, abused and killed in armed conflicts; and children being bought and sold in that terrible form of modern slavery which is human trafficking, which is a crime against humanity."