Former minister Christopher Pyne says his post-politics role with consultancy firm EY does not breach the Ministerial Code of Conduct, a comment made amid a growing feud that has Labor considering a crossbench proposal to support a parliamentary inquiry into lobbying.

Powerful crossbench senator Rex Patrick rebuked Mr Pyne for what were his first detailed comments since The Sydney Morning Herald and The Age revealed last week that he would advise for EY part-time.

Senator Rex Patrick has issued a challenge to Christopher Pyne (above): defend yourself in front of a parliamentary inquiry. Credit:AAP

"I know my responsibilities under the code and I will abide by them," former defence minister Mr Pyne said. "No one has been able to point to any instance of a breach of the code. Asserting something does not make it fact."

The Ministerial Code of Conduct says a minister should not have business meetings with politicians and public servants, including from Defence, for 18 months after leaving office. The code, which is not binding, also says ministers should not "take personal advantage" of private information they had access to while minister.