VATICAN CITY - Pope John Paul II warned against attempts to tamper with what he called "the irreplaceable" institution of marriage-based family, saying Saturday that such efforts would deeply wound society.

John Paul has been an outspoken opponent of gay marriage.

His speech to participants in a meeting of the Vatican's council on family matters did not mention any specific issues. But it appeared to refer to moves by some countries and cities to recognize marriage between homosexuals and to grant social benefits deriving from marriage - such as inheritance or pensions - to cohabiting couples who are not married.

"Family, based on marriage, is a natural, irreplaceable institution and fundamental element of the common good of every society," the pope said. "Whoever destroys this fundamental fabric of human coexistence, by not respecting its identity and by distorting its tasks, delivers a deep wound to society and often provokes irreparable damage."

His remarks echoed declarations in the Vatican's recently issued compendium of church teaching on social issues. That document stated that "no power can abolish the natural right to marriage or modify its traits and purpose."