The Pope has condemned the UK equality bill, saying that it goes against religious freedom and violates "natural law".
He said that the bill could end the right of the Catholic Church to ban gay people from taking senior positions, and urged Catholic bishops to fight it with "missionary zeal".
His comments came after representations from bishops in England and Wales, gathered in Rome, on the place of religion in an increasingly secular society. He said: "Your country is well-known for its firm commitment to equality of opportunity for all members of society.
"Yet, as you have rightly pointed out, the effect of some of the legislation designed to achieve this goal has been to impose unjust limitations on the freedom of religious communities to act in accordance with their beliefs."
The Pope recently confirmed a visit to the UK, which is expected to take place in September. It will be the first papal visit since Pope John Paul II in 1982.