Kevin Rudd's Papua New Guinea refugee plan would fail within weeks because the island nation cannot cope with the 200 Manus Island refugees it already has, protesters at a rally on Saturday heard.
The protest, in Melbourne's CBD, was organised after Australia signed an agreement that no person arriving in Australia by boat without a visa would be settled in Australia. They would instead be processed in Papua New Guinea and settled there if their case was proved.
Co-chair of the Refugee Action Collective, Lucy Honan, told a rain-soaked crowd of about 600 that the rally was the beginning of a "fightback" against the hardline policy.

Protesters at a rally in the city against Prime Minister Kevin Rudd's new asylum seeker policy.
Protesters at a rally in the city against Prime Minister Kevin Rudd's new asylum seeker policy. Photo: Ken Irwin
"This policy, where we send refugees packing to Papua New Guinea, our poor struggling neighbour, is going to fall apart, in practical terms, within the next couple of weeks," Ms Honan said.
"It is not going to happen. Papua New Guinea, cannot, cannot, take the expected 20,000 refugees that are going to approach Australia," she said.
She said the 200 Manus Island refugees sent from Australia were regularly returned to Australia for medical treatment.
"The situation is falling apart," she said.
Ms Honan said refugee groups had successfully fought similar policies under the Howard government.
"We have obviously slipped back a long away, but we can turn that around. We don't need to turn the boats back, we need to turn back public opinion," she said.
Human rights lawyer Jessie Taylor said boats would stop when refugees in Indonesia had a way to apply for a visa to Australia.
Greens senator Sarah Hanson-Young described Friday's agreement as a "rush to cruelty on refugees".
"Unfortunately, Kevin Rudd has shown that he is unable to stand up to the fearmongers," she said.
"And for Papua New Guinea, how atrocious for us to be dumping our considered 'political problems' onto a country that we should be helping. Dumping the world's most vulnerable onto the world's most vulnerable – it is bad policy, it is awful, horrible politics, it isn't just hardline it is hideous."