The Muslim Council of Britain (MCB), an umbrella organisation representing about 500 Muslim groups in the country, has launched a website with an online petition for those who oppose government proposals to change the legal definition of marriage. Currently, this stipulates it must be between a man and a woman. With eight states in the US allowing same-sex marriages and Barack Obama, the president, recently giving them his blessing, Britain is poised to legislate to allow marriage services next year. They are already legal in countries such as Canada, Spain, Portugal, Argentina, Norway, Sweden, Belgium, the Netherlands, Iceland and South Africa. But in Britain, Christians, Jews, Sikhs and now Muslims argue that marriage can only be between a man and a woman, primarily for the purpose of having children. The MCB said that it launched its website - Muslims Defending Marriage - in an attempt to pressure the government, which has begun a public consultation period that ends a week on Thursday. \"It is imperative that the Muslim community does all it can to contribute to this because we have a sacred duty to stand up for marriage and to support those, of whichever faith, that are doing so,\" said Farooq Murad, the secretary-general of the MCB. In 2005, Britain legalised \"civil partnerships\", which offer same-sex couples the same rights in law as heterosexual married couples. However, gay rights groups have campaigned to be allowed to enter into traditional, legally recognised marriages because they say that by failing to do provide for this, the Civil Partnership Act leaves them as second-class citizens. Although few places of worship are likely to give a religious blessing to same-sex marriages, faith groups argue that to put such unions on the same footing undermines and misunderstands the whole basis of marriage. The government insists the new law will not force anyone to carry out marriages for same-sex couples but the MCB website asks: \"Can we contemplate a future in which further calls from the gay lobby will prompt the government to force imams, priests, rabbis and other religious leaders to marry gay people or face prosecution for refusing to do so?\"