Under the new laws, gay partners will benefit from the remaintals-will recognise them as deservingthe same help and information as husbands or wives.
Labour rejected extending similar rights to those who live together but do not have a sexual relationship, for example elderly sisters who have shared a home for many years and who depend upon each other.
Gay partners who break up will have to go through a divorce process identical to that used by married couples. The richer partner may have to pay maintenance.
Family court judge Barbara Simpson said last night that many gay couples do not know they will be subject to divorce laws.
She added: 'We have seen some very costly divorce settlements awarded after relatively short marriages and as the law is exactly the same irrespective of gender, there is no reason to doubt that such precedents will be followed.'
Miss Simpson, a Family Division deputy district judge, said wealthy gay couples could consider taking out a pre-nuptial agreement.