Prime Minister Scott Morrison has written to the head of his department seeking clarification on the ministerial code of conduct in relation to two former high-ranking Liberal colleagues.

Former defence minister Christopher Pyne and ex-foreign minister Julie Bishop have come under fire for jobs they’ve taken since leaving politics.

Government Senate leader Mathias Cormann said on Thursday that Mr Morrison had written to Department of Prime Minister and Cabinet secretary Martin Parkinson for clarification on how the ministerial code of conduct applies to all previous governments.

Senator Cormann said the Prime Minister also asked what actions could be taken in relation to the code, making reference to former ministers in the Morrison government.

Mr Pyne has a new defence-focused role with professional services giant EY, while Ms Bishop has been appointed to the board of an aid contractor.

The code stipulates that ministers must not lobby or have business meetings with politicians or public servants within 18 months of leaving parliament, on matters they dealt with in their final 18 months in office.

Centre Alliance’s Rex Patrick had been pushing for an inquiry into Mr Pyne’s job, but put that on hold after learning Mr Morrison had written to Dr Parkinson.

Opposition Senate leader Penny Wong’s motion was passed asking Mr Morrison to outline what he knew and when about Mr Pyne and Ms Bishop’s jobs.

-AAP