EMBATTLED Turnbull Government frontbencher Stuart Robert has insisted he did not act "inappropriately" during a personal trip to China for a signing ceremony between a Liberal donor and mining firm.
Prime Minister Malcolm Turnbull faced down Labor calls for him to sack Mr Robert on Tuesday.
Mr Robert, then Assistant Defence Minister, has denied any misconduct during the China trip he took during personal leave to attend a signing ceremony between prominent Liberal Party donor Paul Marks and Chinese state-owned company MinMetals.
Reports indicated he may also have met with Chinese government ministers in his official capacity, despite his statements it was a personal trip.
Labor leader Bill Shorten said in parliament that the ministerial code of conduct puts "a blanket ban on ministers providing assistance to companies in a private capacity".
Asked in Question Time about the trip, Mr Robert - now Human Services Minister - said he was confident he did not act "inappropriately" and the matter "has been referred to the highest public servant in the land".
Mr Robert was asked a series of related questions about his involvement on the trip and he repeatedly referred to his previous answer.
Mr Shorten asked Mr Turnbull about the matter, and whether he would "enforce your own standards".
But Mr Turnbull said that "due process, accountability, integrity, that is what we stand for and that is what we will deliver".
Mr Turnbull said the matter was raised on Monday and he had immediately initiated an inquiry by the secretary of the Department of Prime Minister and Cabinet, Martin Parkinson.
The political controversy follows the summer resignation of former minister Jamie Briggs and Mal Brough standing aside from the ministry.
Mr Turnbull has also been considering a ministerial reshuffle in light of those changes in his ministry.
He also attacked Mr Shorten over his alleged role as the head of the Australian Workers Union in reducing workers' pay and conditions in return for payments to the union from cleaning firm Cleanevent.