He went on to tell Campbell that human freedom "can never be realized independently of God but only in cooperation with his loving plan for humanity."

Britain's civil partnership law took effect last week.

Civil partnerships give same-sex couples an opportunity to register their relationships and receive most of the same benefits accorded married couples including pension, immigration, and property rights.

Most of the European Union states already have varying forms civil unions. Only The Netherlands, Belgium and Spain in the EU permit same-sex marriage. Elsewhere, Canada and the US state of Massachusetts allow gay marriage. Vermont offers civil unions and several states have domestic partner laws. Earlier this month the highest court in South Africa gave the government one year to pass a marriage equality law.

Since his election to the papacy in April, Benedict has reaffirmed the Church's anti-gay stand. In June, he issued a stinging condemnation of gay and lesbian families.

Repeatedly driving home his point that marriage can only be a union between man and woman, the Pope called same-sex unions "pseudo-matrimony".

Before becoming Pope, Benedict had long history of attacking same-sex unions. As Cardinal Ratzinger he was the Vatican's most outspoken opponent of gay marriage.

Campbell, a 35-year-old career diplomat, has worked for the British Foreign Office since 1997.

END