Barnaby Joyce says China-Solomon Islands pact an 'intimidating tactic', Jim Chalmers says government has 'dropped the ball'

But the Prime Minister on Sunday would not reveal how the federal government would react to the scenario, as a security pact between China and Solomon Islands sparks alarm in Canberra.

The development, which potentially paved the way for China to establish a naval presence on Australia's doorstep, has seen the government's handling of national security come under fire.

Mr Morrison framed a Chinese naval base in Solomon Islands as unacceptable to Australia and Washington, but did not say how his government would react if that line were crossed.

"We won't be having Chinese military naval bases in our region or on our doorstep," he told reporters.

"Let me first be clear: [Solomon Islands] Prime Minister [Manasseh] Sogavare has been very clear to me saying there will be no such bases. That is what he has said, and so he clearly shares our red line."

Mr Morrison rejected suggestions a cut in foreign aid to Solomon Islands had pushed Honiara closer to Beijing, insisting Mr Sogavare had only ever expressed deep gratitude for Australian support.

The US has warned it will "respond accordingly" to any Chinese base in Solomon Islands, after dispatching a high-level delegation to Honiara last week.

The Coalition has been criticised for failing to send either Mr Morrison or Foreign Minister Marise Payne to Honiara after reports of the deal surfaced, with junior minister Zed Seselja instead travelling for a short visit this month.

Labor foreign affairs spokeswoman Penny Wong accepted China was "much more aggressive and assertive", but accused the Coalition of thumbing its nose at Australia's Pacific neighbours, hinting at more financial support to the region from a Labor government.

Senator Wong said Australia's sluggish approach to climate change, an existential threat to the Pacific, and foreign aid cuts had alienated Solomon Islands.

Asked how a Labor government would approach the Pacific, she said: "We have to shore up our region".

"I can tell you what we wouldn't have done. We wouldn't have cut foreign aid and development assistance," she said.

"We wouldn't have mocked Pacific island nations about water 'lapping at their doors', which is what Peter Dutton did, standing next to Scott Morrison."

Deputy Prime Minister Barnaby Joyce conceded Beijing aimed to expand its capability in the region, warning Solomon Islands to "be really careful" as it tightens ties. "I just hope that China does not get the capacity to set up a naval base, because it's obviously an intimidating tactic to Australia," he told the ABC's Insiders.

But Mr Joyce said he accepted Mr Sogavare's assurances that Honiara would not play host to the Chinese military or damage regional stability.

"I take their word. I'd say: be really careful inviting a totalitarian power into your country, because it is going to affect your sovereignty," he said.

Defence Minister Peter Dutton had earlier warned Beijing had shifted its approach to the region, raising the prospect of "corrupt payments" being made.

But he said specifics were "not something that I can comment on".