Investment board had ports sale doubts

Things are not always as they seem, particularly when it comes to foreign investment.

Chairman of the foreign investment review board Brian Wilson's initial response to last year's proposed sale of Darwin Ports to Chinese firm Landbridge was that it was not in the national interest.

He told a Senate hearing that not being a defence expert, he went back to the Department of Defence and the national security agency three times over the 99-year lease being granted for the strategic asset before giving it the tick of approval.

He was also in discussions with Treasury "until I was satisfied they really had looked at that".

A counter example was when the S. Kidman land sale to foreign investors came up, which Mr Wilson initially felt was not an issue, even taking into account its Anna Creek station was in the Woomera protected area.

"But I've been convinced again by those that really know," he said.

That sale was blocked by Treasurer Scott Morrison on national interest grounds, although Kidman has since reopened the company's sale process to Australian parties.

"The obvious public perception around some of these things and the detailed knowledgeable perception is not always a perfect fit," Mr Wilson told the committee in Sydney on Thursday.