The Department for Work and Pensions has denied trying to encourage staff to vote against Scottish independence after a leaked memo pleaded for employees to "support" the UK government's position over the referendum.

According to a memo written by permanent secretary Robert Devereux, civil servant support for the UK government's position was "legitimate and necessary".

"It is important that, as civil servants, we understand why the Scottish independence referendum is different from elections such as a UK General Election or a European Election," said the memo.

"This is because the UK Government has a clear position to maintain the Union and so it is legitimate and necessary for UK civil servants to support the Government in this objective."

However, the UK government has since hit back: "of course" it is not telling staff how to vote. The letter is "simply [to] set out referendum guidance".

Scottish people will vote in an independence referendum on 18 September, and will be asked the straight "yes/no" question: "Should Scotland be an independent country?"

Latest polls show that the gap between a "Yes" and a "No" vote is rapidly closing but it is still unlikely that a union break will happen.