The Scottish Secretary has given the strongest signal yet that the UK Government is preparing to devolve power over abortion law to the Scottish Parliament.

David Mundell has raised the prospect of Westminster handing over the powers as part of a package of new measures for Holyrood.

Campaigners such as Amnesty International, Human Rights Consortium Scotland and Scottish Women’s Aid fear that such a move to transfer control from Westminster to Holyrood could lead to tougher laws in Scotland and, as a consequence, force Scottish women to travel south to have their pregnancies terminated.

Last week, at the completion of the Scotland Bill’s Committee Stage, the Scottish Secretary announced that, following many hours of intense debate, there would be “substantive changes” made to the legislation.

In an exclusive interview with The Herald, Mr Mundell made clear talks with the Scottish Government would take place over the summer with a view to promoting an agreed line in time for the Report Stage of the Scotland Bill in the autumn.

Abortion was one of the most contentious issues during the all-party Smith Commission negotiations on further powers for Scotland. The cross-party talks almost collapsed after abortion became a "red line" for Labour.

Harriet Harman, the acting party leader, was said to have gone “ballistic” when the prospect was raised.

Ian Murray, the Shadow Scottish Secretary, has made clear a woman's "right to choose should be based on medical evidence and not by where they live" and that, while he accepted the current system needed to be improved, this was best achieved through a “UK framework and should be a debate separate from the constitution".

Mr Mundell pointed out that the Commission had agreed that “in due course” abortion should be devolved.

“There’s no constitutional reason why abortion should not be devolved and the argument was well made in the debate that the Scottish Parliament has the responsibility for end-of-life issues and it has dealt with those very appropriately in terms of due consideration that is given to those issues.

“However, the Commission recommendation was that there should be discussions between the two governments on the abortion issue and those discussions are on-going,” he explained.

The Secretary of State pointed out that an amendment to devolve power over abortion to Holyrood, which was put forward by pro-life Catholic MPs from different parties, was rejected, saying it had "pre-empted" the London-Edinburgh discussions.

“I have agreed with John Swinney (the Deputy First Minister) we will continue those discussions over the summer and we will have something to say in agreement with the Scottish Government by the time we reach Report Stage, so we can set out our response.” The Report Stage could take place as soon as Westminster returns in September.

Earlier this year, the Scottish Government quietly dropped a demand for new powers over abortion, saying it had other priorities.

But Nationalist MPs made clear during the debate they supported the devolution of abortion law to the Scottish Parliament and a party spokesman noted: “As the Smith Commission reported, the parties were 'strongly of the view' that responsibility for abortion should be devolved, given that health as a whole is devolved."

A senior SNP source stressed that while the party did not want to change the current law on abortion – the termination limit in most cases is 24 weeks - he added: "We're in the more powers business."