Image caption Irish singer Sinead O'Connor was ordained as a priest in 1999 by a breakaway church

The Vatican's decision to declare the attempted ordination of women a "grave crime" has been fiercely condemned by women's church groups in the UK.

Pat Brown, of the group Catholic Women's Ordination, said she was deeply shocked and called the change to Church law "a slap in the face to women".

She said of the Pope: "He is not doing himself any favours."

The Vatican says ordaining women is "grave" as is sex abuse, but denied it was equating the two.

The Pope was "talking about paedophiles and talking about women wanting to be priests as a crime against the faith. I cannot understand that language," said Ms Brown.

The Catholic Church teaches that as Jesus Christ chose only men as his apostles, women cannot legally become priests.

But Catholic Women's Ordination says that argument "does not ring true" as women, in particular Mary Magdalene, were among Christ's closest followers.

When he comes to Britain, there will be people who are deeply offended Pat Brown, Catholic Women's Ordination

Sally Barnes, of the Anglican pro-women bishops' group Women and the Church, took the unusual step of speaking out about another denomination's issues, to lend support to women in the Roman Catholic Church.

"We are aware that there are a large number of women not just in England but across the world who have a vocation to the priesthood. There are equally a large number who support them - men and women," she said.

Irish singer Sinead O'Connor caused controversy in 1999 when she became a priest at a ceremony staged by the breakaway Latin Tridentine church in Lourdes.

Pope Benedict XVI is due to visit Britain, at the invitation of the Queen, later this year.

But there are now fears the Vatican's position on women priests may heighten tensions, as the Church continues to struggle with the scandal surrounding child abuse at the hands of Catholic clergy.

"When he comes to Britain, there will be people who are deeply offended. I feel offended by it as a woman," said Pat Brown.

On his four-day trip in September, the Pope will visit London, Edinburgh, Glasgow and Birmingham - in the latter he will attend a Mass to beatify Cardinal John Henry Newman.

His will be the first official state visit by a Pontiff to the UK and the first papal visit since John Paul II's trip in 1982.

Demonstrations are expected but Catholic Women's Ordination - which works within the Church to encourage debate about making it more inclusive - stressed it would not be among them.

'Vulnerable people'

The new Vatican document was released on Thursday, just days after the Church of England's General Synod voted in favour of legislation to consecrate women bishops.

The new measures are expected to be interpreted as a pointed message to Anglicans.

The BBC contacted the Church of England for a reaction, but it said it never commented on the proclamations of other churches.

In the document, the attempted ordination of a woman is listed as a "grave crime" to be handled by the Vatican's Congregation for the Doctrine of the Faith, just as sex abuse is.

Vatican sex crimes prosecutor Monsignor Charles Scicluna said that including the two issues in the same document was not equating them, but was done to codify the most serious canonical crimes which the Roman Catholic Church handles.

"They are grave, but on different levels," he said on Thursday.

The Catholic Bishops' Conference, a permanent assembly of Catholic bishops in England and Wales, said it welcomed the publication of the document.

"Among several revisions to the original text of the 2001 Motu proprio Sacramentorum sanctitatis tutela, the norms clearly demonstrate the Church's concern for the safeguarding of children and all vulnerable people," a Bishops' Conference spokesman said.