Under the Bill as it stands, the Scottish parliament will not be given powers over abortion law and the right to legislate on it will remain with Westminster.

But the bill has come in for severe criticism from Tories and Lib Dems, who argue that because the rest of health policy will be devolved to Holyrood, it makes no sense to exclude abortion.

There is a large Catholic population in Scotland and demand for devolution in this field won support from the Roman Catholic church, which detected an opportunity to press for moves to restrict abortion in Scotland.

But the government argued that a potential restriction might lead to Scottish women seeking abortions in England, as they do in Ireland.

Defeat no.36 in prospect

Opposition parties argued vainly that the Scottish parliament should be free to restrict, liberalise or leave alone the law on abortion as on other matters.

As Lords debate the Scotland Bill's report stage, the Tory amendment - tabled by Lord Mackay of Ardbrecknish - is likely to be the main focus of debate.

On Monday, Lords defeated the government for a third time during the Scotland Bill, over the independence of the judiciary.

It means the government has now suffered 35 defeats by peers since coming to power.