Image copyright PA Image caption Mr Brown claimed plans to restrict the voting rights of Scottish MPs were a threat to the United Kingdom

Former Prime Minister Gordon Brown has accused David Cameron of risking the future of the United Kingdom.

Speaking on the Murnaghan programme on Sky News, Mr Brown described the prime minister as "unstatesmanlike".

Mr Cameron has said Scottish MPs should be denied full voting rights on issues which affect only England and Wales.

Meanwhile, First Minister Alex Salmond has asked for an investigation into the Treasury's role during the referendum campaign.

He believes civil servants disclosed market-sensitive information about RBS.

Mr Brown said: "It doesn't make sense to do what Mr Cameron suggested the day after the referendum, that Scottish MPs would be second status, second class citizens at Westminster, unable to vote on certain key issues like the income tax rate.

"So the Conservatives have got it wrong. I think they're a hundred per cent wrong on this hundred per cent devolution of income tax.

"They've got to understand that their measures are a gift to the separatists, they would play into the hands into the nationalist party, they would drive a wedge between Scotland and England and make the constitution unstable."

Mr Brown had earlier said Labour, Conservatives and Liberal Democrats should be able to unite round his proposals for a "powerhouse parliament" for Scotland.

His call came ahead of House of Commons debates on Tuesday and Thursday.

Media playback is unsupported on your device Media caption The government is outlining proposals for further Scottish devolution in the wake of the No vote, as Jeremy Cooke reports from Dundee.

Financial Conduct Authority

He spoke as Alex Salmond wrote to Martin Wheatley, the chief executive of the Financial Conduct Authority (FCA).

He wants an investigation by the FCA and criminal authorities into Treasury actions during the referendum campaign.

The allegations raised by Mr Salmond concern contingency planning by RBS for a "Yes" vote.

The Treasury is understood to have sent an email about the RBS plans at 22:16 on 10 September.

A meeting of the RBS board which was considering the plans did not, according to Mr Salmond, finish until about 22:40.

Mr Salmond said the timing gives "significant cause for concern".

The Treasury said then they were responding to inquiries from journalists.

It is understood they were contacted by The Sun newspaper after Lloyds had issued a statement about its future. Questions were then put to the Treasury about the future of RBS, which has been based in Scotland since 1727.

They said the story about RBS potentially moving its headquarters had already been reported elsewhere previously.

A Treasury spokesman said on Sunday that it would not be making any further comment on the issue.

Scottish Greens

The Scottish Green Party, holding its conference in Edinburgh, has backed a call to review the party's 2015 UK General Election strategy.

Media playback is unsupported on your device Media caption The Scottish Greens say they've been energised by the referendum campaign

In 2010 the party stood candidates in 19 out of the 59 seats in Scotland.

Co-convener Patrick Harvie said: "The last time the Scottish Greens fought a Westminster election we had around 1,000 members across Scotland, and now that figure is closer to 7,000.

"This extraordinary increase in activist numbers gives us the ability to knock on many more doors, deliver many more leaflets, and to continue the much broader discussion about Green values with the public that took place during the referendum campaign."

He added: "We recognise that it will be an enormous challenge to secure a Green MP in Scotland, as indeed it was for our colleagues in England and Wales to secure the election of Caroline Lucas in 2010.

"But that must now be our ambition, which is why this review is so urgent."