Pope Francis has compared having an abortion to hiring a "contract killer."
"Interrupting a pregnancy is like eliminating someone," Francis said in an address to worshippers in the Vatican.
"Getting rid of a human being is like resorting to a contract killer to solve a problem," he added. "Is it just to resort to a contract killer to solve a problem?"
His comments departed from the prepared text for his homily delivered during his weekly audience on Saint Peter's Square.
In his address, the Argentine pontiff complained of a "depreciation of human life." He cited wars, exploitation and what he called a culture of wastefulness, as well as abortion.
"How can an act that suppresses innocent life be therapeutic, civil or even human?" he asked.
Francis this year opposed a bill that would have legalised abortion in Argentina.
In August a lay campaign group said thousands of Argentine Catholics had renounced their membership of the Church to protest against his opposition to the bill.