Anthony Albanese claims Australia has become less safe in the wake of the Solomon Islands signing a security pact with China.
The opposition leader said the government had dropped the ball on relations with Pacific nations, leading to China increasing its influence over the region.
His comments followed those of former prime minister Malcolm Turnbull, who lashed out at his successor Scott Morrison over the handling of international relations.
Mr Albanese and Mr Turnbull both criticised the government's decision not to send Foreign Minister Marise Payne to handle the situation in the Solomons, opting instead for Pacific Minister Zed Seselja.
"We need a comprehensive plan of engagement with the Pacific and we simply haven't had it," Mr Albanese told Perth radio station 6PR on Tuesday.
"We've dropped the ball, and as a result Australia is less secure."
In an interview on ABC Radio, Mr Turnbull said it was a mistake for Senator Payne not to make the journey to the Solomons.
"This is a hose you have to hold," he told ABC Radio.
"(The Australia-Pacific relationship) needs time and attention, you cannot step away from responsibility ... the buck stops with the Australian government on this because it's adverse and contrary to what our policy objectives were."
Mr Turnbull said the outcome was "an absolute failure" of foreign policy.
Senator Payne said the pandemic had stopped her from travelling but insisted she had still been communicating with her Pacific counterparts.
A visit to the Solomon Islands "may or may not happen" during the election campaign but Australia's relationship with the nation remains on good terms.
"This is a strong partnership but it does not detract from the fact that governments will, of course, make their own sovereign decisions," she told ABC Radio.
"It would be naive at best for Australians to operate on the basis that we can march into other people's countries and dictate and tell them what to do."
The opposition has sought to boost ties with Pacific nations, on Tuesday announcing a multi-part strategy to improve relations.
Labor foreign affairs spokeswoman Penny Wong said the opposition would always work alongside the US to secure the area.
"The US is the indispensable partner in our region, and the nation when it comes to the security of the Indo-Pacific," she told reporters in Darwin.
"We can't simply handball our mistakes to the US. The reality is this is on Australia. The Australian government led by Mr Morrison has left a vacuum."
The foreign minister said the Solomon Islands had reiterated Australia remained its security partner of choice.
Australian Associated Press
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