In his first significant foray into domestic politics since since he lost office, Mr Rudd accused Mr Turnbull of doing everything he could to appease the "mad right" of the Coalition.

His attack was a departure from the convention whereby former prime ministers generally avoid criticising their successors.

On Sunday, the Coalition said it would rush new laws into Parliament next week that would introduce a lifetime ban on all visas for asylum seekers who have attempted to come to Australia by boat, even if they are genuine refugees and seek to come as tourists decades later.

The ban would apply to all adults detained at the Manus Island or Nauru detention centres from July 19, 2013, when Mr Rudd said anyone seeking to come to Australia without a visa would never settle here.

Opposition leader Bill Shorten strongly criticised the proposal – claiming it was designed to appease the political far right – but stopped short of ruling out support for the plan.

Mr Rudd's comments are likely to increase pressure on Mr Shorten to rule out support for the proposed laws.

In a scorching opinion piece for Fairfax Media, Mr Rudd said that " Turnbull's latest legislative folly should be opposed", and that the Prime Minister had "now repudiated virtually everything he once stood for" in order to hang on to his job after a "near-death experience in the July election".

"This is both bad policy and bad politics: on policy, the far right in Australia represent the worst of the xenophobic, nationalist and protectionist wave that we now see raging across Europe and America; while on politics, appeasement of political thugs like Abbott, Dutton, Abetz, Andrews and, depending on which way the wind is blowing, Morrison, only embolden the far right to demand more, not less," he writes.

" This measure is about the politics of symbols, designed to throw red meat at the right, including the Hansonite insurgency, and to grovel to the broad politics of xenophobia. Turnbull, once an intelligent, global citizen, knows better."

Mr Rudd, now based in New York, goes on to say that the 2013 deal with PNG for refugees to be processed on Manus Island – struck during his brief return as prime minister – had been intended to run for one year only, and was designed as a mechanism to break the "gathering momentum of the people-smuggling industry".

"Neither Abbott nor Turnbull have honoured the refugee protections outlined in the 2013 agreement because it was not in their domestic political interests to do so," he writes, saying the deal should not have been renewed.

The Coalition, however, had junked the principle of "non-refoulement" – which stops refugees being sent back to a place where they face harm – and " mis-represented the 2013 agreement as permanent, rather than as a temporary one-year measure ", he writes.

Crucially, he says, the Turnbull government had also "cruelly refused the offer from New Zealand to resettle 150 refugees annually from Manus and Nauru, when the 2013 agreement explicitly provides for resettlement to third countries".

"I have kept silent on Australian domestic policy debates for the last three years. But this one sinks to new lows. It is pure politics designed to appease the xenophobes," Mr Rudd concludes.

Mr Rudd's extraordinary intervention came after Mr Turnbull rejected claims from One Nation leader Pauline Hanson that refugees were not welcome in Australia, because many were economic refugees seeking generous welfare.

In recent days, Mr Turnbull has frequently recalled that in 2009, while opposition leader, he had "begged" Mr Rudd not to change John Howard's border protection policies.

Mr Turnbull has argued the new visa ban is necessary because his government is trying to resolve the problem created by Mr Rudd – prompting the former prime minister's intervention.

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