Andrew Robb insists he has not breached any of his responsibilities as a former cabinet minister in his new job with the Chinese operator of Darwin Port.
Mr Robb, who resigned as Australia's trade minister in February, has been criticised for joining Landbridge as a senior economic adviser two months ago.
Labor this week raised concerns about the appointment, questioning whether the company may have in turn gained access to sensitive government information.
But Mr Robb defended his position, labelling such suggestions as wrong, disingenuous and pure speculation.
"I understand very clearly as a former senior cabinet minister the responsibilities that I've got and that are required of me and I've got no intention of breaching those," he told reporters in Sydney on Wednesday.
"I intend to act with integrity."
Mr Robb said he had to maintain secrecy about meetings and procedures both in and outside of government over many decades and this was no different.
"I'm required not to divulge or to act upon or to get personal benefit from anything which is not known to the general public or some of the public - I'm very clear on that," he said.
He put down the criticism to politics and said it was not going to stop him from fulfilling his duties.
