The UK government may allow the monarch to marry a Catholic and give female heirs an equal claim to the throne, the government said in what would be a reversal of discriminatory laws going back 300 years.

Prime Minister Gordon Brown and the Queen have held talks on changing the 1701 law on succession to the throne that was drawn up at a time of widespread hostility to Roman Catholics.

The Act of Settlement bars royals from becoming king or queen if they "profess the popish religion or shall marry a papist."

Mr Brown said the reform is overdue, but will be complicated by the need for agreement among all 53 Commonwealth countries.

"In the 21st century, people do expect discrimination to be removed," he told the BBC. "There are clearly issues that have got to be dealt with not just in Britain but ... across the whole of the Commonwealth."

Cardinal Cormac Murphy-O'Connor, head of the Catholic Church in England and Wales, wants the law to be reformed, although he thinks there are more important issues facing the country.

"It is anachronistic and discriminatory and he is sure it will be repealed at some point," his spokesman said.

"However, it is not something that the Church is actively lobbying for. It is not top of our priorities."

A Buckingham Palace spokesman declined to comment.

The law was passed to preserve the Protestant succession after the Glorious Revolution of 1688 when Britain's last Roman Catholic King James II was deposed by his Protestant daughter Mary and her Dutch husband, William of Orange.

Opposition to Catholics in Britain had its roots in Henry VIII's split from Rome in the 16th century, suspicion of the Pope and Catholic France and Spain and the 1605 Gunpowder Plot by Catholic gentry to blow up Parliament in London.

Under the statute, women automatically slip down the line of succession to the throne if a male heir is born and royals can't take the throne if they marry a Catholic.

In a statement, Mr Brown's office said that, while it hopes to reform part of the law, there are no plans to drop the ban on a Roman Catholic from becoming king or queen.

"This is a complex issue," it said. "There is no question of changing the constitutional role of the monarch or of changing the role of the Church of England as the established church."

MP Chris Bryant, deputy leader of the House of Commons, has been asked to examine the reform.

Graham Smith, of the anti-monarchy group Republic, welcomed the proposed reforms, saying: "The more we try to apply modern standards to this insane institution the weaker it will become."