The Prime Minister has ordered an investigation into the new jobs of former MPS.

Christopher Pyne and Julie Bishop - the former defence and foreign affairs ministers, respectively - have accepted roles with consulting firms in the weeks since quitting politics.

Labor says they may be in breach of the Statement of Ministerial Standards, which states former ministers cannot take lobbying jobs for 18 months after leaving office.

Senate leader Mathias Cormann says PM Scott Morrison has written to the secretary of his department to investigate whether Mr Pyne and Ms Bishop broke the rules.

The careers of all former ministers, from both the Coalition and Labor, are expected to be assessed.

“As part of this, [Mr Morrison] has sought advice on actions that can be taken to ensure compliance with the code,” Senator Cormann said.

“Additionally, as part of this advice, [Mr Morrison] has asked the secretary about the application of the provisions of the Foreign Influence Transparency Scheme Act 2019 to the activities of former ministers and elected representatives.”

Ms Bishop was the foreign affairs minister when Australia’s foreign aid spending was privatised, and now works for one of the biggest beneficiaries of that policy.

Labor's Penny Wong says Ms Bishop's new job with private aid contractor Palladium breaches the ministerial standards.

Mr Pyne was the defence minister, and now consults for multinational business advisers Ernst and Young (EY), again, a major beneficiary of government funds.