The head of the Roman Catholic Church in Scotland, Cardinal Keith O'Brien, has challenged Westminster politicians to examine their consciences over recent parliamentary votes on early life issues.

At a Mass in the crypt of the House of Commons on Wednesday, the Cardinal warned MPs and peers that society was living in a "time of confusion" and reminded them of the need to follow their conscience, even if this meant that they encounter difficulties in their political roles.

"It has struck me that for all the Church's calls for recognition of the inviolability of conscience the sad reality is that the vast majority of politicians have given support to various attacks on human life with apparent lack of reproach from conscience," he said.

"What does one say then, in the face of those who without guilt condemn the innocent in the womb, show disregard for family life and play God with the building blocks of life?"

Cardinal O'Brien's criticism comes just weeks after Parliament voted in favour of controversial legislation that will allow scientists to create and destroy animal-human embryos for research and so-called "saviour siblings". MPs also voted to retain the upper legal limit for abortion at 24 weeks.

The Cardinal went on to criticise Catholic MPs and peers who go against their beliefs by towing the party line on early life issues.

"We cannot but help notice that consciences among even some who ostensibly see themselves as loyal Catholics or champions of the life have been dulled even so far as to acquiesce with what is euphemistically called a right to choose," he said.

Quoting St Paul, the Cardinal reminded politicians of their responsibility as Christians to witness: "God's gift was not a spirit of timidity, but the Spirit of power, and love, and self-control. So you are never to be ashamed of witnessing to the Lord.

"That is precisely what all involved in political life are called upon to do at this present time."