Prime Minister Tony Blair is coming under further pressure to scrap the ancient rule which prevents Catholics from ascending the throne or marrying the monarch.

A week ago the Scottish Parliament unanimously backed a motion calling for that part of the Act of Settlement to be revoked.

Now a motion designed to highlight the issue again will be presented at Westminster.

Growing support

It describes the law as ''anachronistic and offensive'' and calls on MPs to join MSPs in calling for its abolition.

So far it has only got two signatures, but the number is expected to grow.

Despite the keenness for change shown by MSPs, any move to amend the act would need to be implemented by the Westminster parliament.

When the debate first surfaced, Mr Blair ruled out early action, saying any change would be too complex to instigate.

However, that did not prevent former Conservative Scottish Secretary, Lord tary, Lord Forsyth of Drumlean, from making his own bid to have the law changed.

His attempt was short lived and his motion was voted down in the House of Lords 14 to 65 against.

The chief critic of the move, Lord St John of Fawsley said a single peer should not bring in such a momentous change without the support of the government and the opposition parties.

The leader of Scotland's Catholics, Cardinal Thomas Winning, called the act an "insult" to Roman Catholics and welcomed the Scottish Parliament's vote on the matter.

The debate was sparked at the end of October by Lord James Douglas Hamilton - Tory whip in the Scottish Parliament - when he wrote to Mr Blair asking him to lift the act, which he described as "anachronistic and anomalous injustice".