Scotland's most senior Roman Catholic faced a furious political backlash last night after he launched an outspoken attack on what he described as the "evil trade of abortion".

Cardinal Keith O'Brien was criticised by politicians, health workers and pro-choice campaigners after he called for the Abortion Act, passed exactly 40 years ago, to be redrawn to make it harder for women to have terminations.

The cardinal said the number of terminations in Scotland was the equivalent of two Dunblane massacres every day and urged the Scottish Executive to put pressure on Westminster to change the laws on abortion.

He also warned Catholic politicians that they should not take Holy Communion if they support the legislation in its current form.

In a sermon marking the 40th anniversary of the 1967 Abortion Act, he issued a warning to Catholic politicians of "the barrier such co-operation (on abortion) erects to receiving Holy Communion".

But critics and even fellow Catholics warned the cardinal not to use the sacraments as a "political weapon".

Liberal Democrat MSP Jeremy Purvis (Tweeddale, Ettrick and Lauderdale) said: "I think it's very unfortunate he has chosen to use extreme and provocative language, and a hectoring and bullying tone against MSPs and MPs who every day balance their own consciences against what they think are the best interests of their constituents."

Terry Sanderson, of the National Secular Society, said: "There is an implied call to Catholic politicians and health workers to place Catholic doctrine above the wishes of the electorate. This is undemocratic and unacceptable."

The head of the UK's leading sexual health charity said the cardinal did not know enough about abortions to speak out on the matter. Ann Furedi, chief executive of British Pregnancy Advisory Service, said: "The cardinal has every right to hold his views. He obviously doesn't have to have an abortion, or provide one."

Making his comments in a sermon during Mass at St Mary's Cathedral in Edinburgh yesterday, Cardinal O'Brien said the Abortion Act had been founded on "lies and misinformation masquerading as compassion and truth" and had led to a situation where the equivalent of a classroom full of schoolchildren were being killed in Scotland every day.

"That's like two Dunblane massacres a day in our country and it's going on and on," he said.

Around 150 parishioners attended the lunchtime service, with only one choosing to heckle the cardinal by shouting "It's lies" midway through the sermon.

Undeterred, the cardinal added: "We need to build, once again, a society which joyfully accepts new life.

"The abortion industry has impacted massively on the values of our society as its proponents continue to spread their culture of death. There is acceptance of a philosophy, which permits the destruction of children in the haven of their mother's womb."

Cardinal O'Brien said it was particularly incumbent on Catholic MPs and MSPs to do what they could to change the laws on abortion. "They must consider their own consciences and whether or not they can approach the altar to receive Holy Communion," he said.

The SNP executive has so far refused to be drawn on the issue, pointing out that abortion laws are reserved to Westminster. But speaking after Mass, Cardinal O'Brien said that was unacceptable and that they should make "representations" to their counterparts in London urging them to amend the legislation.

A senior Nationalist MP, Pete Wishart said: "The Catholic Church is, of course, entitled to its point of view on this issue, but the last thing Scotland needs is to end up like the US where churches and faith groups have an undue influence on political debate."

Cardinal O'Brien was supported by Michael McMahon, Labour MSP for Hamilton North and Bellshill. He said: "Catholics are only required to go with their own consciences, to assess things from their own perspective and use their conscience as a guide."