Alex Salmond (pictured, Reuters) has said there would be an "inevitable investigation" over allegations that the Treasury leaked "market-sensitive" information about Royal Bank of Scotland's proposal to register itself in England if Scotland votes for independence.

The First Minister and SNP leader said the alleged BBC briefing by a "Treasury source" was "a matter of extraordinary gravity", and urged the BBC to co-operate with the probe that must follow.

Speaking at a press conference for international journalists in Edinburgh, Salmond said: "A Treasury source told the BBC that it had discussed the plans with RBS.