LABOUR has accused Alex Salmond of giving up on independence as one of his former special advisers claimed supporters may have to accept a "slower pace" to achieve it.

Duncan Hamilton said supporters of a split from the Union may have to back the devo-max option if it remained the most popular in 2014.

But the Yes campaign leader, Blair Jenkins, insisted he would campaign only on the issue in what opposition parties claimed was a split with the SNP's stance. This came as it emerged Mr Salmond has described the second question option as a "very attractive argument".

Scottish Labour leader Johann Lamont accused the SNP of a "con" saying: "The fact that Alex Salmond wants a second question shows he has given up on winning the first. Any question he designs will not be intended to enhance devolution but will be designed to lead to the break-up of the UK through the back door."

Polls suggest devo-max, or extra powers for Scotland, remains the most favoured option for voters.

Mr Hamilton suggested yesterday that gradualist supporters of independence could even campaign for devo-max as a step toward their ultimate goal.

He said the Yes campaign "is clearly for independence but, as gradualists, most independence supporters (like me) also see the merit in working with the majority opinion, which is currently overwhelmingly in favour of a second question on the maximum devolution short of independence.

"We want Scotland to move forward united, and if that means accepting a slower pace towards independence, so be it."

Scottish Conservative leader Ruth Davidson said Mr Salmond's refusal to rule out a second question "is further proof that his attempt at presenting a united front within his separatist movement is unravelling by the day".

Mr Jenkins called for the No campaign to reject donations from those not on the electoral register in Scotland.

A Scottish Government spokesman said: "The Scottish Government's policy is independence, and the straightforward, fair question on independence is the one we have outlined in the consultation paper.

"At the same time, we recognise that there is substantial support across Scotland – from individuals and organisations – for increased responsibilities for the Scottish Parliament short of independence."