Christian and Muslim groups are to stage a torchlit protest outside the House of Lords tonight against a proposed new gay rights law that they say would force them to "actively condone and promote" homosexuality.

The demonstration outside the Palace of Westminster will coincide with a Lords debate on the proposed introduction of new equal-treatment rules in Northern Ireland, which are set to be replicated elsewhere in the UK in the coming months.

The legislation, known as the Sexual Orientation Regulations, would ban discrimination in the provision of goods, facilities and services on the basis of sexuality in a similar way to the rules on gender and race discrimination.

It would mean that hotels could be prosecuted for refusing to provide rooms for gay couples, and parishes obliged to rent out halls for civil partnership receptions. In a twist to the new rules, gay bars would not be able to ban straight couples.

However, Christian and Muslim groups have protested against the rules, which they say would force them to go against their religious beliefs.

Tonight, the Lords was due to debate the Sexual Orientation Regulations specifically for Northern Ireland. If they are passed, the regulations will be added to the Government's Equality Act, which completed its Parliamentary stages last year.

The demonstrators fear that if the Northern Ireland regulations are allowed to go through as they are tonight, it will have very serious ramifications for the rest of the country. This is because the Government is planning to draft its England and Wales regulations by April and, if the Northern Ireland regulations pass this evening, sources in the Lords say it is almost certain that the England and Wales regulations will be the same when they are drafted.

A total of 10,000 people have already signed a petition to the Queen organised by Christian Concern for Our Nation, part of the Lawyers' Christian Fellowship, which complains that the new law would have the consequence of "discriminating heavily" against Christians of all backgrounds and denominations.

In particular, Catholic adoption agencies have said they fear they may be forced to allow gay couples to adopt.

Some black churches have also added their voices to the protest, saying that pastors and churchgoers would go to jail rather than accept rules that would mean they had to open their meeting halls to gay lobby groups.

Muslim organisations have also put together a petition protesting against the rules.

The gay rights campaigner Peter Tatchell, from the group OutRage!, said today that the demonstration would be the result of "scaremongering, lies and hypocrisy".

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