Prime Minister Malcolm Turnbull has revealed he has asked his department for advice about the conduct of Human Services Minister Stuart Robert.

Key points: Mr Robert visited Beijing in 2014 on an unofficial trip while Assistant Defence Minister

Mr Robert visited Beijing in 2014 on an unofficial trip while Assistant Defence Minister He attended a signing ceremony for an agreement between the Chinese company Minmetals and Australia's Nimrod Resources

He attended a signing ceremony for an agreement between the Chinese company Minmetals and Australia's Nimrod Resources Nimrod Resources' executive chairman Paul Marks is a Liberal Party donor

Mr Robert visited Beijing in 2014, at which time he was the assistant defence minister for the Abbott government.

During the trip Mr Robert attended a signing ceremony for an agreement between the Chinese company Minmetals and Australia's Nimrod Resources.

In a statement, Minmetals said Mr Robert congratulated the company on the deal on behalf of the Defence Department.

"On behalf of the Australian Department of Defence, Assistant Minister Robert extended his congratulations on the cooperation between Nimrod and Minmetals," the statement reads.

"He expressed his full confidence in this cooperation … adding that the good relationship between Nimrod and the Australian Government will effectively promote the success of the cooperation."

The statement goes on to say that Mr Robert, "presented to Chairman Zhou a medal bestowed to him by Australian Prime Minister in honor [sic] of remembrance and blessing".

It also reads: "Assistant Minister Robert awarded the letter of appointment of the committee to General Manager Wang Jionghui."

Stuart Robert (centre) attended a meeting in China where a prominent Liberal donor finalised a mining deal. ( Supplied: Minmetals )

Pictures of the ceremony show Mr Robert and members of the company standing behind a table with the Australian and Chinese flags on it.

Nimrod Resources' executive chairman Paul Marks is a Liberal Party donor and Mr Robert has declared shares in Evolution Mining, another company Mr Marks is linked to.

The Federal Opposition had said Mr Turnbull should sack Mr Robert if it was proven he breached the ministerial code of conduct, but the Prime Minister today stood by his frontbench minister.

He told Question Time he had confidence in Mr Robert, but had sought further advice.

"I can confirm that I have asked the secretary of my department for advice in relation to the statement of ministerial standards," he said.

Mr Turnbull said the matter would be dealt with thoroughly and "in accordance with the code".

'A shocking beat-up': Scott Morrison

Labor frontbencher Stephen Conroy said Mr Turnbull should sack the Minister if the facts were as they appeared.

"We need a full copy of the video that will have been made of this event," he said.

Paul Marks (right, with Tony Abbott) donated $340,000 to the Liberal Party over the past financial year. ( ABC News )

"Ultimately if all the facts are that Stuart Robert has used his position as a minister to promote a company that has made major donations to the Liberal Party … then he has to go, and Malcolm Turnbull should show leadership and uphold the ministerial code of conduct."

Mr Robert's spokesman said the Minister was on leave and rejected the company's assertion he spoke on the Department's behalf.

"Mr Robert visited China when on approved leave and in an entirely private capacity," the spokesman said.

"Mr Robert did not speak on behalf of the Department of Defence."

The Minister did not claim flights to Beijing on his entitlements register for the period.

He is close to Treasurer Scott Morrison, who this morning described the story as a "shocking beat-up".

Marks donated $340,000 to Liberal Party over past year

Foreign Minister Julie Bishop told Channel 7 she understood from Mr Roberts' office it was a "personal visit".

"Of course that's perfectly acceptable," she said.

"I don't know how you can make a secret visit to China … China knows a great deal of what's going on when it comes to its borders, but nevertheless I understand it was a private visit.

"Matters of the ministerial guidelines and code of conduct are matters for the Prime Minister and Prime Minister and Cabinet."

The mining magnate hit the headlines last year after Mr Abbott claimed a taxpayer-funded travel allowance on a day he attended Mr Marks' birthday celebrations in March.

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