Mr Morrison on Sunday made clear he wouldn't tolerate a Chinese military presence on Australia's doorstep, arising from Beijing's new security pact with the Pacific nation.

Mr Morrison said Solomon Islands Prime Minister Manasseh Sogavare had assured him that wasn't on the table, and he believed that meant the country shared Australia's "red line".

However, Mr Morrison hasn't clarified how Australia would react if that line was crossed.

Opposition defence spokesman Brendan O'Connor said Mr Morrison's comments signalled a change in "tone and rhetoric" on the security deal.

Mr O'Connor said Labor would seek fresh briefings from government agencies.

"Clearly there are concerns about the decision for the Solomon Islands to enter into an agreement with China," he told ABC's RN Breakfast.

"We need to be briefed on what the government's contemplating beyond just those terms. The words used [by Mr Morrison] obviously sound relatively heightened."

"We'd need to know more from ... agencies about that."

The security pact between China and Solomon Islands has become a major federal election issue, as Labor continues to slam the Morrison government over its failure to thwart the deal.

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Mr O'Connor was pleased Mr Sogavare had provided assurances that China wouldn't be allowed to build a military base in the country.

But he cautioned that that didn't necessarily mean it couldn't happen in the future under the terms of the security deal.

"From what I've been told there is still an opportunity for that to happen, that is the presence of Chinese naval and other defence assets," he said.

Earlier, 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".

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