An independent Scotland could require its own currency or be forced to join the euro following a Yes vote in 2014, analysis of the options by the Treasury is expected to warn.

The report marks the next step in a campaign against separation by the Coalition Cabinet including the Chancellor George Osborne.

The Scottish Government has insisted Scotland would keep the pound if it breaks off from the UK.

Earlier this year, a working group set up by Alex Salmond found the retention of sterling would be an attractive option both for an independent Scotland and the rest of the UK.

It is thought the Treasury report will set out four potential currency options for Scotland, including setting up its own currency and joining the euro as a requirement of EU membership.

The report is the second in a series of 13 planned by Whitehall.

The first warned that, if Scotland left the UK, it may have to re-apply as a new member to join the EU.

The Scottish Government is also preparing a series of reports into what it believes will be the impact of independence.

The Fiscal Commission Working Group, appointed by the First Minister, reported in February that an independent Scotland would be able to sustain its own currency but added there would be "practical difficulties" establishing it in the first place.