Civil servants working to “break up the United Kingdom” would be “unusual and worrying”, the head of the civil service has said.

Simon Case, the Cabinet Secretary and head of the Civil Service, said on Tuesday that civil servants in Scotland could be issued with new guidance within “weeks” after complaints that about 20 officials were supporting Jamie Hepburn, the Scottish independence minister.

Mr Hepburn’s appointment by the new First Minister Humza Yousaf in March drew criticism from unionists, who argued that constitutional change was not a devolved matter.

Asked whether it was appropriate for civil servants in Edinburgh to work on devolved matters, Mr Case told the House of Lords’ Constitution Committee: “We are looking at some of these specifics as we speak.

Spending by the Scottish Government on the independence minister is also the subject of an investigation by the advocate general for Scotland, Lord Stewart, who is the UK Government’s adviser on Scots law.

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