Yes Scotland will wait until next month before deciding if the case for independence needs an alternative to monetary union.

At a Yes board meeting last week, the Sunday Herald understands its chief executive, Blair Jenkins, was in a minority in holding the line that there was no need for an alternative, despite currency union being ruled out by Westminster.

The board agreed to return to the subject next month if opinion polls showed any weakening in support for independence.

Yes Scotland is a cross-party movement and many senior members support an independent Scotland at some stage ditching the pound and using its own currency.

However, at Monday's meeting of the Yes advisory board, it is understood Jenkins repeated the SNP's line that the campaign should stick to the currency union plan and that Westminster's block is a bluff.

He was supported by Tasmina Ahmed-Sheikh, an SNP candidate and Alex Salmond loyalist. Deputy First Minister Nicola Sturgeon, who would also have backed the Government position, did not attend.

The furthest Jenkins has deviated from the currency union position was a reference to "other options that an independent Scotland could pursue".

One Yes insider said: "Blair is caught in the middle. He is not SNP but he is the chief executive of an organisation effectively run by the SNP. It is difficult for him."

The source added that there were "varying degrees of scepticism" inside Yes about Jenkins' position on currency and that within the board the CEO was in a clear minority.

A Better Together spokesperson said: "The Yes Scotland board don't buy the SNP's failed currency union plan, but they are being forced to go along with it."

A spokesperson for Yes Scotland said: "The advisory board are all agreed that the only sensible way forward into independence is with sterling.

"It will be for all parties to make their cases for the currency they prefer in the 2016 elections for the first elected government in an independent Scotland."