A "rainy day" fund has been opened by Westminster to allow the Scottish Government to put money aside in case its revenues drop when prospective new tax powers take effect.

In 2016, the Scottish rate of income tax will be reduced by 10p in the pound, if Scotland votes no to independence, and the Scottish Parliament would then set the remaining tax rate.

Provisions in the Scotland Act 2012 also allow the Scottish Government to set aside up to £125 million over five years in a cash reserve, which can be accessed if future tax revenues are lower than forecast.

The Scotland Office said the SNP Government could now make its first payment into the cash reserve.