The Roman Catholic Church in Britain on Sunday will call on Catholics to oppose the government's plans to legalize gay marriage in the country, the UK edition of the Huffington Post reported.

The UK's Conservative Party last September unveiled plans to make gay nuptials legal in Britain before 2015. The Conservative Party, Britain's largest political party, governs in coalition with the Liberal Democrats. Prime Minister David Cameron, who helms the Conservative Party, supports the move, saying it promotes conservative values such as commitment.

Great Britain currently recognizes gay and lesbian couples with civil partnerships, which offer most of the legal protections of marriage.

The government is expected to release a consultation document detailing its plans on the law next week.

A letter to be distributed in churches calls on Catholics to reject the government's “profoundly radical” plans.

“We understand marriage to be a call to holiness for a husband and wife, with children recognized and loved as the gift of God,” the letter reads.

“We have a duty to married people today, and to those who come after us, to do all we can to ensure that the true meaning of marriage is not lost for future generations.”

A video of Archbishop Vincent Nichols of the Diocese of Westminster reading the letter was released Friday on the Internet. (The video is embedded in the right panel of this page. Visit our video library for more videos.)

(Related: Pope Benedict calls on U.S. bishops to oppose gay marriage.)