The Auditor General's Office says it is keeping an eye on developments in the Pansy Wong case but has not yet decided whether it is appropriate for it to investigate.
The government faces further questions in Parliament today about Sammy Wong's taxpayer-funded trips to China after revelations he attended a factory opening while supposedly on a private visit.
Sources also claimed Mr Wong had been involved in arranging meetings and providing translation services during talks with Chinese companies involved in rail deals in New Zealand, just days before leaving for China on his MP wife's taxpayer-funded travel perk, for a trip which he claimed was a holiday to research family roots.
But his wife, former Cabinet minister Pansy Wong, denied either case involved personal business.
Prime Minister John Key has told Labour that if it has concerns it should lodge those with the Auditor General.
The Wongs have been forced to pay back $474 for wrongly using the MPs' travel perk but were cleared of systematically rorting the subsidy, which was not allowed to be used for business purposes.
The latest allegations raise questions about the findings of an inquiry called by the Speaker, Lockwood Smith, which found that taxpayers subsidised the Wongs' international travel to the tune of more than $54,000 over the past decade.
Labour's Pete Hodgson tabled papers in Parliament showing that on June 28, 2005, Mr Wong was on the stage with former prime minister Jenny Shipley - a business associate of Mr Wong - during a foundation-laying ceremony at an Alpha Group factory in Fujian province.
Mr Hodgson said Mr Wong had helped Mrs Shipley "launch a $40 million investment into a biotechnology centre, in which Mrs Shipley has shares".
According to a report released last week, the purpose of Mr Wong's travel in 2005 was for him to search family roots in Fuzhou, the home of his parents.
Mrs Wong said Mr Wong had known Professor Gao of Alpha Group for 10 years, and he had been invited to the opening as a family friend.
"Sammy had no business interests with Professor Gao or the Alpha Group at the time."
However, in November this year Mr Wong had taken up a role as agent for Alpha Group, Mrs Wong said.
The trip involving the factory opening was the second Mr Wong took to research his family roots.
On March 8, 2005, he arranged for flights, leaving on March 14, to visit Hong Kong and Shanghai, returning 30 days later.
A spokesman for state-owned KiwiRail said: "We understand in March 2005 Mr Wong was engaged by PPD, a company with links in China, to arrange meetings in New Zealand for CNR.
"At that time the owners of CNR met the then-owners of the rail business in New Zealand, Toll NZ."
However, Mrs Wong said that was not true.
"He was not engaged by anyone."
KiwiRail negotiated the supply of 20 locomotives from CNR.
- The Dominion Post
Should David Cunliffe lead Labour again?Related story: Cunliffe, Robertson trade blows