More than a third of Scottish firms may relocate outside Scotland in the event of independence, a poll suggests.

A total of 36% of companies would consider moving following a yes vote on 18 September, while 40% would not, according to a Survation poll of 100 Scottish businesses for the Scottish Mail on Sunday. Only 15% of those surveyed said an independent Scotland would be "beneficial" to their business, while 45% said separation would be "harmful".

Three in four (75%) said it was essential or important for their business that an independent Scotland remain in a currency union with the rest of the UK. That option has been ruled out by the chancellor, George Osborne, backed by Labour and the Liberal Democrats leaders. The firms, said to have total sales of more than £15bn, took part in the poll on condition of anonymity.

Concerns about independence have been raised by several firms based in Scotland in recent weeks, including Lloyds Banking Group, Barclays, Standard Life, Royal Bank of Scotland, Alliance Trust and Aggreko. The heads of major oil companies Shell and BP have also stated they would like to see Scotland remain in the UK.

Blair McDougall, director of the pro-union Better Together campaign, said: "The fact that so many businesses would consider relocating from Scotland if we left the UK is a big concern. This poll confirms what companies like Standard Life and Alliance Trust have already made clear. Independence would cost Scottish jobs and put up costs for families here. It's a risk we don't have to take."