The number of people in Australia waiting for a visa decision has swelled to a size equivalent to the population of Hobart.

Key points: The number of people in Australia on bridging visas has more than doubled in the past five years

The number of people in Australia on bridging visas has more than doubled in the past five years Experts wonder what impact this new influx of workers is having on the labour market

Experts wonder what impact this new influx of workers is having on the labour market Migrants appear to be taking advantage of delays to stay in Australia longer

According to the Department of Home Affairs, 229,000 people on bridging visas were in Australia in March. Hobart's population at the latest census was 222,000.

And a new report has identified the impact of this group on the labour market for the first time.

The Committee for Economic Development of Australia (CEDA) analysed the census to find this group had an unemployment rate of about 20 per cent.

That is high compared to the Australian average, but it still means four in five who were looking for work were working — equivalent to many tens of thousands in the labour force.

A migrant is granted a bridging visa when one visa has expired but they are still waiting for their new visa application to be finalised.

Processing times for visas and the number of migration-related court appeals have increased in recent years. These prompt delays, meaning more people remain on bridging visas.

Melinda Cilento, chief executive of CEDA, said that temporary migrants had improved Australia's prosperity overall, though the growth in bridging visas did warrant closer inspection.

"The community's looking at that and wondering how well the system's working and is it actually working the way that we want it to work," she said.

"Many of these people on bridging visas still have working rights — that's also a question the community will be asking: Is this the outcome we're looking for?"

Senator Linda Reynolds, representing the Home Affairs Ministers, told the Senate on Tuesday that the growth in bridging visas was caused by increased arrivals generally and she anticipated further growth.

"As numbers increase, of course you will get an increase in all sorts of categories of people arriving, and making claims to stay," she said.

"So you would expect that number to grow merely by the fact of the amount of people who come here by air."

Behind the growth

A recent parliamentary committee highlighted the growing trend for Malaysians arriving in Australia on a tourist visa then applying for asylum.

In June 2014, just 7 per cent of Malaysians temporarily in Australia were on bridging visas, according to Department of Home Affairs figures.

By March this year, the share had risen to 34 per cent.

Now more Malaysians are on bridging visas than on any other visa, even the popular subclass 500 student visa.

But it is not just an issue with the Malaysian group — the number of bridging visas has increased for most nationalities.

Peter McDonald, a professor in demography at the University of Melbourne, said the bridging visa cohort had "blown out" and was now "enormous compared to any past history".

"For a long time the numbers on bridging visas were seen as an indicator of the government's efficiency in processing applications because the vast majority of people on bridging visas are applying for permanent residence," he said.

Immigration Minister David Coleman sought to highlight "declining" onshore protection claims.

"These fell by 12 per cent in the 2018-19 program year, a result of the Government's focus on stopping unmeritorious claims."

Professor McDonald said the growth was due not only to the growing number of people arriving by plane then claiming asylum — such as the group of Malaysians identified — but also the lengthening queue for partner visas.

"Normally, in the past, [spouses] get their permanent residency immediately," Professor McDonald said.

"But the Government has now introduced a long delay in that process, and there are now about 80,000 spouses of Australian citizens waiting for their permanent residence."

Senator Reynolds said on Tuesday the Government was taking "appropriate steps" to deal with airline arrivals.

She said there had been a 32 per cent decline in the number of protection visa applications from Malaysians in the first five months of 2019 compared to the same period in 2018. Across all nationalities, the decline was 20 per cent.

Labour market impact

A separate report from the University of Adelaide released in March found the horticulture sector was reliant on Malaysian workers, but also that workers were vulnerable to exploitation.

As part of a series of interviews, it reported one stakeholder saying "the Malaysians … are the ones who are exploited".

"When you know there's Malaysians on a farm, very few of them could be legal," the stakeholder said.

A labour hire contractor was reported to have said Malaysians "just use the visitor visa to come to Australia and they stay longer than three months and just work in Australia, and that's what happens … they are very hard workers and then they become illegal people".

Malaysians can travel to Australia on an official tourist visa obtained online.

Australian border officials are refusing entry to 20 Malaysians at Australian airports every week, to address what has been dubbed an "orchestrated scam".

The working holiday maker or 'backpacker' visa, the most popular low-skill visa in Australia, is not available to Malaysians.