Firms working on long-term public sector building contracts will continue to be paid in sterling in the event of a Yes vote, according to the Scottish Government.

It came after a new clause was put in public and private sector infrastructure contracts emphasising payments will "remain" in sterling throughout the life of the project.

Pro-UK campaigners yesterday claimed the deals drawn up by Scottish Futures Trust (SFT) quango showed that ministers needed to allay fears an independent Scotland would not continue to use the pound.

Labour MSP Jenny Marra, speaking on behalf of Better Together campaign, said: "The SNP have finally admitted there is no guarantee that Scotland will keep the pound after 2014.

"They think another currency is such a risk they are guaranteeing businesses that the Scottish Government will pay its debt in sterling even if we end up with another Scottish currency."

The SFT makes deals to build and run schools and hospitals, often over a 25 year period and has more than £3 billion of deals on its books.

The contract now states: "All invoices under this Agreement shall be raised in Pounds Sterling."

First Minister Alex Salmond's plans to keep the pound as part of a currency union have been been dismissedby Chancellor George Osborne. A government spokesman said: "Contracts are currently paid in sterling and as we have set out with independence Scotland will continue to use the pound as part of a currency area with the rest of the UK."