Scott Morrison is following in Donald Trump's footsteps by refusing to sign a non-binding migration agreement which Australia helped draft.
Australian officials have been heavily active in negotiating the wording of the UN Global Compact on Migrant over the past two years.
But the prime minister says the UN pact would compromise Australia's border security and immigration settings.
"It doesn't distinguish between those who illegally enter Australia and those who come the right way," he told 2GB radio on Wednesday.
"I would never allow something to compromise our borders, I worked too hard to ensure that we weren't in that position."
The agreement is supposed to support safe, orderly and regular migration.
Mr Morrison argues the government has already achieved these goals.
The Refugee Council of Australia lashed out at the prime minister's "nonsense" excuses for refusing to sign the agreement.
"Australia will join a small group of governments which are each trying to appeal to, or appease, minority far-right political movements within their countries," its chief executive Paul Power said.
"It is hard to see the Australian government's decision as anything other than posturing for some political gain, as the facts do not align with the prime minister's claims."
The US, Israel, Austria, the Czech Republic, Poland, Croatia, Hungary and Bulgaria have also refused to sign the agreement.
Home Affairs Minister Peter Dutton said the compact was primarily focused on Europe, where asylum seekers were drowning at sea in the Mediterranean.
"I think this compact was largely directed at that problem, not towards our part of the world," he told Sky News.
Mr Dutton said Australia had stopped boat arrivals and drownings at sea through hardline border protection policies.
"We're not going to surrender that, we want our sovereignty to remain intact," he said.
However, the pact explicitly affirms the sovereign right of states to determine their national migration policies.
The Australian government is also worried about how the courts could interpret the pact.
"We're concerned about whether or not it starves us as a sovereign nation of the ability to decide the way in which we can return people under the compact," Mr Dutton said.
"Certain obligations could be imposed where we needed to support people once they'd been returned back to a country of origin."
Opposition Leader Bill Shorten said Labor was not fussed whether the government signed the pact or not.
"Obviously we'll take the advice of our security experts on what we should and shouldn't do," he told reporters in Sydney.
Australia signed a similar refugee pact earlier this month, but Mr Dutton said that document contained only "benign" language.
Save the Children is urging Australia to work towards global solutions on migration.
"There is unprecedented movement of people, including vulnerable children, around the world which Australia cannot ignore," policy director Mat Tinkler said.
The UN migration pact is due to be formally adopted at a meeting in Morocco next month.
Australian Associated Press