LABOUR is mounting a major challenge to block controversial plans that would see abortion laws devolved to Scotland.

The move would scupper the handover of one of the most significant powers since devolution.

Labour argue that the transfer is being rushed through without a proper review of the potential consequences.

But the move will prove controversial, not least because it will be attempted in the unelected House of Lords.

Labour's frontbench in the Lords will try to force ministers to delay the move for a year and order a consultation into its likely effect.

David Cameron's government wants to devolve abortion to Holyrood, but his party does not have a majority in the Lords, where Tory ministers have suffered a series of setbacks in recent months.

A defeat at the hands of peers last year forced George Osborne back to the drawing board on plans to cut in-work tax credits.

Plans to devolve abortion law have triggered fears there could eventually be two systems, with different rules or time limits in which to seek a termination, on either side of the Border.

Former Labour leadership candidate Yvette Cooper is among those to express concern that women could be forced to travel for abortions at a vulnerable time.

Campaigners have also voiced fears that more women in Scotland will be targeted by anti-abortion campaigners.

First Minister Nicola Sturgeon has said that she has no plans to change the existing legal position on abortion.

However, opponents point out that she cannot tie the hands of her successors.

Those who back the idea say that it is an anomaly that MSPs currently have powers around end of life legislation but not abortion.

Labour says a review was promised by the cross-party Smith Commission into extra powers, set up in the wake of the independence referendum.

A Scottish Labour source said: “We raised concerns regarding the devolution of abortion in the House of Commons.

"The measure was passed, but we still believe it is important that the consultation that was promised by the Smith Commission is carried out.

"This measure (in the Lords) would allow 12 months to properly consult.”

Many within Labour believe the outcome of any review will force a rethink.

Abortion proved one of the most explosive issues during the Smith negotiations.

At one point Labour threatened to walk out of the talks if it were included in the final agreement.

In the end, Smith concluded that "further serious consideration should be given to its devolution and a process should be established immediately to consider the matter further".

However, last summer the Conservative and SNP Governments agreed to move ahead with the handover.

The change was confirmed by Tory Scottish Secretary David Mundell when he appeared in front of a Westminster committee of MPs.

In response Labour MPs angrily protested that it was not in the "gift of any one minister" to make such a decision.

The idea of a one-year delay was first suggested by a group of backbench Labour peers, but has now been officially adopted by the party.

Abortion Rights Committee Scotland said that the "space" opened up by Mr Mundell’s announcement had seen a rise in activity by anti-abortion groups in Scotland.

A spokesman for Amnesty said that it, alongside a number of women's rights' organisations, had raised concerns about the process for devolving abortion to Scotland when it was first suggested, but added: "We are where we are and there doesn't seem to be a clear case for delay".

She added that the focus now would be on monitoring the tactics of anti-abortion groups.

Emma Ritch from Engender, the Scottish feminist organisation, said: "Engender and other women's organisations had initial concerns about the inclusion of abortion within the Smith Commission agreement, and then the Scotland Bill.

"Throughout two rushed and hasty processes, it had seemed as though politics, and not women, was at the heart of decision-making.

“Despite these concerns, Engender has always been positive about the possibilities that devolving abortion to Scotland may bring. We are currently working with colleagues in women's and human's rights organisations to identify how abortion healthcare might be improved in Scotland following devolution.

"Our conversations with UK Government and Scottish Government do not suggest any particular reason why delaying devolution for a year would be helpful."

Kirsty Blackman, the SNP's spokesman on the House of Lords, said: “The Labour Party’s patronising attitude to Scotland shows just how desperately out of touch they are.

"The Scottish Parliament has a proud history of passing progressive laws on matters of health, equality and women’s rights.

"The idea that male-dominated Westminster with its backwards-looking ways is somehow better placed to legislate on these matters is pure nonsense.

"The notion that unelected Labour Lords will now seek to override Scotland’s MPs and block these powers because they think they know better is simply outrageous – and the people of Scotland will take a dim view of these moves.”

Ms Cooper said she backed a delay.

She said: "This major change to the long standing abortion law framework is happening without enough consultation. Having different laws in Northern Ireland and the rest of the UK already forces women to travel away from their families for health advice or abortions at a sensitive time, and no one wants to see more women travelling for such important appointments.

“This vital issue for women's health and women's lives needs careful thought, not to get rushed through because it is just caught up in the politics of nationalism.”

A Scotland Office spokesman said : “The Smith Commission were of the view that abortion law should be devolved to the Scottish Parliament and there is no constitutional reason why it should not be. The abortion laws will not change at the point of devolution. The current legislation will remain in force unless and until the Scottish Parliament decides to change it. The First Minister has made a very clear statement that the Scottish Government has no plans to change abortion law in Scotland.”