Prime Minister Malcolm Turnbull has downplayed concerns from United States president Barack Obama about the leasing of the Port of Darwin to a Chinese-owned company.

The ABC understands Mr Obama and Mr Turnbull discussed the issue during a bilateral meeting on the sidelines of this week's APEC Summit in Manila.

Mr Turnbull, speaking in Manilla, said the fact the port was being privatised was no secret and was announced publicly last year.

"The fact that Chinese investors were interested in investing in infrastructure in Australia is also hardly a secret," the Prime Minister said.

"The NT Parliament conducted an inquiry. I had a committee that looked into it earlier this year and it reported in April and recommended that the ... NT Government consult ... with FIRB [Foreign Investment Review Board] and with the Australian Defence Department."

Mr Turnbull said the department had no concerns because "it didn't affect the Australian Defence Forces".

"And under our legislation, the Department of Defence or this Federal Government can step in and take control of infrastructure like this in circumstances where it's deemed necessary for purposes of Defence," he said.

Earlier, Northern Australia Minister Josh Frydenberg told RN Breakfast that Defence agencies would deal appropriately with any concerns the US may have.

"I'm sure that our Defence agencies will be closely working with our American counterparts to ensure that any of the concerns that they have are dealt with appropriately, and that any concerns that they may have are taken into account," he said.

According to The Australian Financial Review, Mr Obama told Mr Turnbull the US should have been given a "heads up about these sorts of things".

Concerns have been raised within the Defence community about the $506 million deal with the Landbridge Group.

The Australian Strategic Policy Institute claimed the company was a commercial "front" for the Chinese Communist Party, and was part of China's bid to increase its influence in northern Australia.

Both the federal and Northern Territory governments have downplayed security concerns.

Treasurer Scott Morrison told reporters in Sydney he does not think the US has chided Australia on the issue.

"We enjoy a very strong relationship with the United States, I think that's been on display in recent times," he said.

"I meet with the [US] ambassador about these issues from time to time as all ministers do about various issues.

"We enjoy an exceptional relationship."

Defence Department secretary Dennis Richardson told a Senate estimates hearing in October the sale had been closely scrutinised by security and intelligence agencies.

"Defence does not have any security concerns about the sale of the port to Chinese interests," he said.

"I note that it is a commercial port; it is not a naval base."