Whitehall departments have been told to notify the head of the civil service of any senior officials holding paid jobs outside government by the end of the week.
Simon Case, the Cabinet Secretary, said there was “acute concern” at the top of the service about the issues that have emerged in the David Cameron lobbying affair.
It follows the disclosure that former government chief commercial officer Bill Crothers worked as a part-time director at Greensill Capital while still in Whitehall.
In a letter to permanent secretaries, Mr Case said that while there was a role in government for people with outside expertise, it was essential for the “integrity and impartiality” of the civil service to be maintained.
In particular, there had to be “transparency and full proper management” of any outside interests, and those that conflicted with officials’ obligations under the Civil Service Code are not permitted.
Mr Case wrote: “If you come across any instances of senior civil servants holding remunerated positions or other interests outside government which might conflict with their obligations under the code please bring them to mine and (Cabinet Office director general of propriety and ethics) Darren Tierney’s attention immediately and, at the latest, by the end of this week.”
Mr Case said it was essential for departments to “engage fully” with the review commissioned by Boris Johnson, being carried out by legal expert Nigel Boardman.
“If, as Nigel Boardman completes his review, he identifies areas where we as a civil service have made mistakes, it is important that we are honest about these and learn from them,” he added.
The move comes as the Commons Public Administration and Constitutional Affairs Committee (PACAC) prepares to take evidence from the head of the body which vets appointments taken up by ministers and senior officials after they leave government.
Former cabinet minister Lord Pickles, who now chairs the Advisory Committee on Business Appointments (Acoba), had previously demanded to know why Mr Crothers’ appointment with Greensill was not cleared with his committee.
He was told by the Cabinet Office that because Mr Crothers began working for the firm before he left his job in government he was not required to do so.
Ahead of the hearing on Thursday, the PACAC chairman William Wragg said he was concerned that Acoba was “fairly toothless” – particularly when it came to appointments taken by former officials.
“We are taking these matters seriously and will be pursuing them without fear or favour,” he told the BBC Radio 4 PM programme.
“The heart of it has been the interface between government, public sector and business. I think it has been far stricter for former politicians than it has been for senior civil servants.”