Former foreign minister Julie Bishop has strongly defended the private sector jobs she has accepted since quitting politics, but suggested ministerial standards could be bolstered by banning serving frontbenchers from meeting with former cabinet colleagues.

Key points: Both Julie Bishop and Christopher Pyne insist they are fully compliant with the Statement of Ministerial Standards

Both Julie Bishop and Christopher Pyne insist they are fully compliant with the Statement of Ministerial Standards Ms Bishop says her work with aid contractor Palladium is centred almost entirely on governance, not specific projects

Ms Bishop says her work with aid contractor Palladium is centred almost entirely on governance, not specific projects A recent review found neither Ms Bishop nor Mr Pyne had breached rules in taking on their new positions

Ms Bishop and former defence minister Christopher Pyne have come under fire for taking on jobs in industries that overlap with their former portfolios.

Both insist they are fully complying with the Statement of Ministerial Standards, which bans former ministers from using information they've obtained in office for private gain, and from lobbying government officials on issues relating to their portfolios for 18 months.

Appearing before a Senate inquiry on Thursday, Ms Bishop noted the rules were voluntary and could not be legally enforced, but said they could be "strengthened" by placing the responsibility on serving politicians.

"The onus could and should be placed on current, serving officials," she said.

"Cabinet ministers are in control of their diaries, they determine who they will and will not meet, who they will take calls from and who they will not.

"So if the onus were placed upon the current serving ministers and officials to not hold meetings with former ministers, to not be lobbied, then they would be subject to the ongoing scrutiny of the Parliament.

"And then one would not need to hold a senate inquiry on these voluntary guidelines with private citizens as I am."

Christopher Pyne caused an uproar when he took a consultancy job advising on defence business. ( ABC News: Matt Roberts )

Ms Bishop has taken on a number of jobs since quitting politics but attracted criticism for accepting a non-executive director position with the aid contractor Palladium.

Pyne's post-politics job 2 March 2019 - Christopher Pyne announces retirement from politics

2 March 2019 - Christopher Pyne announces retirement from politics 8 April 2019 - Mr Pyne meets EY defence industry leader Mark Stewart

8 April 2019 - Mr Pyne meets EY defence industry leader Mark Stewart 11 April 2019 - Prime Minister Scott Morrison calls the election for 18 May

11 April 2019 - Prime Minister Scott Morrison calls the election for 18 May 17 April 2019 - EY offers Mr Pyne a job as a consultant

17 April 2019 - EY offers Mr Pyne a job as a consultant 20 April 2019 - Mr Pyne accepts the offer

20 April 2019 - Mr Pyne accepts the offer 18 May 2019 - Federal Election is held

18 May 2019 - Federal Election is held 7 June 2019 - Mr Pyne starts the new job

While she refused to reveal the pay packet, the former foreign minister explained she would be focused almost entirely on governance and accountability and not on specific projects.

Mr Pyne caused a similar uproar when he took a job with consultancy firm EY, advising on defence business, triggering this Senate inquiry.

Mr Pyne disagreed with Ms Bishop about the need to strengthen the ministerial standards, but also insisted he was fully aware of his obligations.

A recent review by Martin Parkinson, the former head of Prime Minister and Cabinet, cleared both former frontbenchers, finding no evidence that they had breached the rules in taking on the new positions.