THE Prime Minister faced Opposition calls for him to sack one of his frontbenchers after revelations Queensland MP Stuart Robert travelled to Beijing to witness a mining deal with a Liberal Party donor.
News Corp reported on Monday Mr Robert, then assistant defence minister, made the trip in 2014 to witness the signing of the mining deal between Chinese state-owned company MinMetals and Australian resources company Nimrod Resources.
Nimrod Resources chairman Paul Marks, a significant donor to the Liberal Party, attended. Mr Robert said Mr Marks funded his trip, which he took in his "private capacity".
News Corp papers reported Mr Robert also held shares in Nimrod Resources and he was a "close friend" of Mr Marks.
While there was no allegation of misconduct, the revelations of the trip follow the frontbench resignation of Jamie Briggs and frontbencher Mal Brough standing aside over the summer.
Labor's Stephen Conroy said on Monday the trip seemed to be a "clear conflict of interest", calling on Mr Turnbull to make a decision on Mr Robert's future.
Mr Turnbull has asked for advice from the secretary of his department over the matter, including whether Mr Robert's actions were consistent with the ministerial code of conduct.
He said he took such matters "very thoroughly and very seriously".