Pope Benedict XVI warned today that liberal family values were threatening the future of humanity, in a veiled reference to homosexual marriage and adoptions by gay couples.

"Policies which undermine the family threaten human dignity and the future of humanity itself," the pontiff said in a speech at the Vatican.

"The family, based on the marriage of a man and a woman ... is not a simple social convention, but rather the fundamental cell of every society," added the 84-year-old pontiff.

Humanity is also compromised by laws that "not only permit but at times even promote abortion for reasons of convenience or for questionable medical motives," Benedict said.

The pope said he was pleased that recent EU rulings banned patenting processes on human embryonic stem cells and condemned prenatal selection on the basis of sex.

Benedict XVI is a firm champion of the family, which he says must play a bigger part in the education of young people in respecting Christian values.

The Vatican frequently condemns countries that recognise gay rights.