Image copyright PA Image caption Gordon Brown said he did not believe the break-up of the UK was inevitable

Former Prime Minister Gordon Brown has said he believes the next 12 months could determine the long-term fate of the union between England and Scotland.

Mr Brown said the union was in "mortal danger" unless the UK government considered modifying their plans for English Votes for English Laws.

The Conservatives should also change their position on welfare top-up powers for the Scottish parliament, he said.

The UK government said it wanted to bring the "whole country together".

Mr Brown, speaking at the Edinburgh International Book Festival, said he did not believe the break-up of the UK was inevitable, but feared the damage already done could be "irreversible".

"Now, almost a year on from the referendum we can detect three potentially fatal flaws in the Conservative government's approach to Scotland and the Union," he said.

"The most immediate is the refusal to grant the Scottish Parliament full top-up powers on welfare as Shadow Scottish Secretary Ian Murray has demanded in defiance of the recommendations of the Smith Commission and the vow.

"Second, the Conservative policy of English votes for English laws would create two classes of MPs - the majority who vote at all times and the Scots who are excluded from key votes on some issues - making the UK home to the first elected body in the world to treat one of its constituent parts - Scotland - as 'half in, half out' of its law-making process."

The UK government is currently clarifying its plans to give England's MPs a veto over English laws, with a vote delayed till September.

Mr Brown said the third flaw was the Conservative's "readiness" to "turn on the tap of English nationalism".

A UK government spokeswoman said: "We want all the parts of our United Kingdom to work together, with better inter-governmental relations between the UK government and the devolved governments.

"We are delivering on our commitments to give more power and responsibility for the Scottish Parliament, within a strong United Kingdom.

"This is a simple issue of fairness within the UK, that makes sure that representatives from each nation are able to have a say on legislation that is specific to them."