Green Party Leader Elizabeth May says Canada should take diplomatic steps to denounce Australia's hardline refugee policies, calling the country's offshore detention practices "appalling."

May is sponsoring a new electronic petition to the House of Commons that presses Australia to admit the asylum seekers it has detained for months — or even years — in offshore island processing centres. Failing that, the petition calls on Canada to welcome Australia's unwanted asylum seekers here.

May said her own view is that Australia's approach is the worst among modern democracies, and that Canada must use diplomatic levers to protest its prolonged detention of asylum seekers on the island of Nauru.

"It's an unimaginable hell on earth for the immigrants who are placed there by the Australian government," she told CBC News.

"It's essentially an open-air prison, and it only speaks to the desperation of the places people came from that they would still head for Australia and wind up on Nauru."

The petition criticizes the Australian government's deployment of military forces to intercept boats filled with migrants, who are then detained in offshore processing centres on Nauru and Manus Island in Papua New Guinea.

It also points to reports from humanitarian organizations and the media about inadequate conditions and incidents of physical and sexual abuse.

"These events and conditions have a detrimental effect on the mental and physical health of refugees, however, no medical treatment or support is provided to them," the petition reads, adding that many who are deemed legitimate refugees are still denied entry.

Mass global migration

Countries around the world are grappling with a mass migration crisis as millions of people flee conflict and persecution — or, in some cases, go on the move to find better living conditions.

Australia's approach to asylum seekers stands in stark contrast to Canada's. Here, thousands are illegally crossing from the U.S. into Canada outside official border checkpoints to sidestep an immigration border pact with the U.S. called the Third Safe Country Agreement.

That has prompted growing calls to either suspend the agreement or to apply it across the entire border. The Liberal government has said that such a move would only drive people to more remote, and more dangerous, crossing points.

Green Party leader Elizabeth May says Australia's approach to asylum seekers, including prolonged detention in offshore processing centres, is "appalling." (Adrian Wyld/Canadian Press)

The Australian High Commission in Ottawa sent CBC's inquiry to Canberra and was not able to respond before publication.

Last month, Australian Prime Minister Malcolm Turnbull defended his government's treatment of migrants, saying it is Australia's "sovereign right" to control its borders. Doing so, he said, is key to maintaining successful multiculturalism and public support for immigration.

Turnbull said his government is "absolutely determined" to ensure the only people who come to Australia are those who come with the government's consent. Tighter controls are also needed to fight the human smuggling trade, unauthorized arrivals and tragic deaths at sea, he said.

Michael Small, who served as Canada's ambassador to Australia between 2010 and 2014 and now teaches at Simon Fraser University, said Australia has a long history of being open to migration and has one of the highest populations in the world of people born outside the country.

Manage border, welcome migration

That policy traditionally has enjoyed broad public and political support — but there is also a strong desire on the part of successive governments and the Australian public to make sure the border is properly managed and that control is retained over refugees chosen for resettlement, he said.

"When illegal or irregular migration tests Australia's ability to manage that, it touches a real political nerve," Small said. "Different Australian governments have struggled to reconcile their compassionate desires and international legal obligations with that need to protect their own sovereignty and manage their borders. That's the context of what they're trying to do at the moment."

According to the UNHCR, people who arrive in Australia without a visa are subjected to punitive measures that can significantly impair their mental health and well-being — including a prolonged determination process that can take up to four years and a lack of free legal assistance.

"Negative political rhetoric and the resulting community stigmatization of this group of asylum-seekers has also had a harmful impact on them," reads the UNHCR website.

'Australia's got it right'

Joe Bissett, a former longtime federal immigration official and researcher, said Australia's approach serves as a strong deterrent and it does not deserve international scorn. Countries like Canada are helping the wrong people by welcoming asylum seekers instead of assisting more legitimate refugees, he said.

"I think Australia's got it right and we've got it wrong," he said. "If you keep taking them in, they'll keep coming."

Once they're in the country, Bissett said, it is extremely difficult, time-consuming and costly to remove unsuccessful refugee claimants from Canada.

More than 28,000 asylum seekers have crossed the border into Canada irregularly since the beginning of last year. Fewer than one per cent of them have been removed from the country.

With no easy solutions and growing global anxiety, May said she worries that other countries, including those in Europe, could follow Australia's model. She said the world must find better ways to cope with what will be a growing problem.

"Eventually, unless we have a dramatically improved global reaction to the climate crisis that's effective, we'll be seeing whole island nations losing their population and looking for places to settle," she said. "So we need to figure out an approach that's both compassionate and sensible."