Landbridge, the Chinese operator of the Port of Darwin, has trumpeted its 99-year lease and the subsequent acquisition of Margarita Island, located by the Atlantic entrance to the Panama Canal, as key to the Chinese government's ambitions to build a "maritime economic corridor" as part of its multibillion-dollar "One Belt One Road" infrastructure roadmap.

Mr Robb's appointment comes despite strategic and security analysts having warned Australian parliamentarians that the free-spending global infrastructure push has a political as well as an economic dimension, as part of an attempt by Beijing to create a strategic bloc to counter the United States' ascendancy in the region.

The appointment was announced on Landbridge's website on September 2, exactly two months after Mr Robb retired as the MP for Goldstein in the July 2 election.  In the announcement, Mr Robb said the "globalisation" process of Landbridge had left a "profound impression" and that he looked forward to "composing beautiful chapters" together with the company.

Landbridge's billionaire founder Ye Cheng said Mr Robb would bring valuable international experience and vision and that he hoped all employees would "stay true to the mission", quoting an oft-repeated comment made by Mr Xi during a speech marking the Communist Party's 95th anniversary in July.

"I know the [media] is getting very excited about this," Mr Robb told Fairfax Media when reached by telephone. "[But] I've got a commercial arrangement," he said, before declining to comment further because he was in a meeting.

Geoff Wade, an analyst at the parliamentary research library who tracks China's growing influence in Australia and the region, said in an August parliamentary briefing paper that Beijing's plans to spend billions on infrastructure in the region, including northern Australia, was in part a bid to use its entrenched economic clout to advance its strategic interests, including its claims over the disputed South China Sea.

"It is an economic strategy by the Chinese state to get themselves and their [state-owned enterprises] and their major corporations economically engaged with Australia so that Australian policy decisions will begin to be sympathetic to the [People's Republic]," Mr Wade told Fairfax Media.

"Having people who know the decision makers and influence decision makers, people who are trusted by the people in power … I think Robb's quite important to them in this respect."

Mr Robb, who has run a private consultancy since leaving parliament, is also on the advisory board of the Australia-China OBOR Initiative, which promotes economic opportunities provided by the Chinese government's One Belt One Road plan.

Mr Robb has been active in China since his retirement from parliament, meeting with Communist Party officials in Fujian in September to discuss One Belt One Road opportunities together with delegations from Mozambique and Malaysia. Just last week, he met with Chinese One Belt One Road officials and vice-minister for commerce Wang Shouwen in Beijing.

Prime Minister Malcolm Turnbull demurred when asked whether it was appropriate for Mr Robb to accept the role. He said his former trade minister had not raised the issue with him before taking on the job.

"Andrew Robb was an outstanding trade minister," Mr Turnbull told reporters on Monday. "But Andrew's left the parliament and he's pursuing a career."

Former ministers are banned from lobbying the Australian government for 18 months. Mr Robb resigned as trade minister in February before leaving parliament at this year's election in July.

"Andrew has said he's aware of the ministerial code of conduct and he'll abide by it," Foreign Minister Julie Bishop told the ABC.