More mud has been slung at Liberal minister Stuart Robert over his links with Chinese businesspeople.

Mr Robert has been under fire for over a week after it was revealed he attended a meeting with senior Chinese officials, and witnessed a mining deal with a Liberal Party donor, both while allegedly on holiday in China in 2014.

The deal was between Chinese company Minmetals and and Australian firm Nimrod Resources, whose executive chairman Paul Marks is a major Liberal Party donor.

A statement from Minmetals after the meeting said Mr Robert had congratulated the company on the deal on behalf of the Defence Department, of which Mr Robert was the assistant minister at the time.

“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 says Mr Robert; “presented to Chairman Zhou a medal bestowed to him by Australian Prime Minister in honor [sic] of remembrance and blessing... [and] awarded the letter of appointment of the committee to General Manager Wang Jionghui.”

Photos from the ceremony show Mr Robert and officials from both companies signing documents around a table with the Australian and Chinese flags on it.

Mr Robert was apparently on personal leave for a whirlwind tour of three continents over seven days in 2014 taking in China, Israel and Croatia, but News Corp media outlets say his official request documents did not say he would be meeting with ­Chinese officials or attending a signing ceremony.

There are loud calls for Mr Robert to explain himself, as it would be a clear breach of the ministerial code of conduct if he was operating for private interests in his official capacity.

But the take-down continues, with News Corp this week reporting that Mr Robert organised a dinner in his Parliament House office in 2013, which was attended by Tony Abbott (the opposition leader at the time), shadow resources minister Ian Macfarlane, Chinese business mogul Li Ruipeng , and major LNP donor Paul Marks.

Reports say Mr Marks requested the gathering be set up so that the foreign businessman could meet key figures of the LNP just three months before the 2013 federal election.

The revelations mean the pressure is mounting on Prime Minister Malcolm Turnbull to act against Mr Robert, who is currently Human Services Minister.

The Department of Prime Minister and Cabinet has been asked to investigate if the trip had breached the Ministerial Code of Conduct, with head of the department Martin Parkinson due to deliver his findings today.