Gordon Macintyre-Kemp, the chief executive of Business for Scotland, said independence campaigners had to “up their game” to persuade more people of the case for separation.
Macintyre-Kemp said the priority for Yes campaigners should be to convince voters of the merits of independence rather than arguing about the date on which a second referendum should be held.
His intervention came amid splits in Nicola Sturgeon’s SNP on the timing of a second poll.
SNP depute leader candidate Christopher McEleny has said a second referendum should be held within 18 months – a position backed by Angus Brendan MacNeil, MP for Na h-Eileanan an lar.
Others have urged a more cautious approach, with the Perth and North Perthshire MP Pete Wishart coming under fire from activists for suggesting that public antipathy towards a second vote was pushing voters away from the SNP.
When asked about indyref2 timing, Macintyre-Kemp said: “We think that’s a complete red-herring. What needs to happen is that organisations who support independence like Business for Scotland need to up their game and campaign more proactively.
“We need to increase the support for independence, which is exactly what we are going to do.”
Macintyre-Kemp said Business for Scotland would be stepping up its campaign in an attempt to move polling for independence above the 50 per cent mark.
“We are going to have a major push on that over the next few months. We hope to increase support for independence into the 50s, so we can say to the SNP we’ve hit the criteria for a new referendum. You don’t think about timing, you just campaign.
“We are training activists. We are pulling together a set of policies and a road map to prosperity with the powers of independence. We will be campaigning on that, putting up posters, distributing leaflets.”
The SNP is expected shortly to publish its Growth Commission, which will act as a blueprint for the economic case for independence. Chaired by former SNP MSP Andrew Wilson, it will tackle issues – such as the currency to be used in an independent Scotland – which were seen as a weak point for the party during the 2014 campaign.
Last year Sturgeon “reset” her referendum plan after a backlash against her proposal to have one by spring next year. The First Minister delayed referendum legislation but still said it was likely there would be one by 2021.
Scottish Conservative chief whip Maurice Golden said: “Business for Scotland needs to understand that there is absolutely no appetite for another referendum. Support for independence is dropping and most Scots just want to move on from the constitutional division of the past.
“Instead of wasting their time on this pointless exercise they should just accept the result of the 2014 vote and move on.”