Former Australia PM Tony Abbott has said Europe should follow Australia and close its borders to migrants fleeing Middle Eastern conflicts.
Mr Abbott made the comments in London, where he was speaking at the second annual Margaret Thatcher lecture.
He said "misguided altruism" was "leading much of Europe into catastrophic error".
Under Mr Abbott, Australia introduced border controls that stopped migrant boats reaching the country.
Hundreds of thousands of people have now fled conflicts in the Middle East - mostly Syria - and sought asylum in European countries.
The UN says most arrivals are not economic migrants, but people fleeing war and persecution. Most are arriving by boat before walking across Europe.
In his first major speech since being ousted by his party, Mr Abbott said: "No country or continent can open its borders to all comers without fundamentally weakening itself."
He was speaking to an audience of ministers and members of the governing Conservative party at London's Guildhall.
"There are tens - perhaps hundreds - of millions of people, living in poverty and danger who might readily seek to enter a Western country if the opportunity is there," Mr Abbott said.
"Who could blame them? Yet no country or continent can open its borders to all comers without fundamentally weakening itself.
"This is the risk that the countries of Europe now run through misguided altruism," Mr Abbott said, according to a copy of his speech.
Strict border controls were a key policy of the Abbott government but attracted international criticism, particularly for the use of off-shore detention centres.
Mr Abbott has credited them for saving the lives of migrants by dissuading them from making perilous sea crossings.
He urged European leaders to emulate the policy of turning back boats.
"It will require force; it will require massive logistics and expense; it will gnaw at our consciences - yet it is the only way to prevent a tide of humanity surging through Europe and quite possibly changing it forever," he said.
Australia's 'stop the boats' policy:
- The previous Labor government reintroduced offshore processing in Nauru and Papua New Guinea in September 2012 - a policy it had ended in 2008 - whereby it pays outsourced contractors to operate and provide security at temporary detention camps for asylum seekers on the Pacific islands
- It also reached a deal with Papua New Guinea that any asylum seekers judged to be genuine refugees would be resettled in Papua New Guinea, not Australia
- The current Liberal-National coalition government adopted Labor's policies and expanded them, introducing Operation Sovereign Borders, which put the military in control of asylum operations
- Under this policy military vessels patrol Australian waters and intercept migrant boats, towing them back to Indonesia or sending asylum seekers back in inflatable dinghies or lifeboats
- In 2013 some 300 boats carrying illegal migrants reached Australia. In 2014 the number was just one
Mr Abbott also said many of the people currently displaced throughout Europe were economic migrants.
"The Australian experience proves that the only way to dissuade people seeking to come from afar is to not let them in," he said.