Ahead of a meeting with Australian Prime Minister Malcolm Turnbull this weekend, Prime Minister John Key said up to 1000 criminals could eventually be deported to New Zealand.
He will ask for the threshold at which a person is deported to be lowered in recognition of the special transtasman relationship.
Mrs Ah Loo said her organisation had helped about 32 newly-arrived Australian deportees in the past three months - a huge increase from around 60 in the 12 months before that.
"We can't sustain it, it would financially ruin us," Mrs Ah Loo told the Herald. "The inhumane detentions is one issue. Our issue is that they are landing today."
When PARS receives a call from immigration police, it sends a staff member to the airport to meet the deportee - often a new arrival who has not lived in New Zealand since they were a baby or toddler, and who has no support here.
PARS staff will help the person sign up to bank accounts, benefits, an IRD account and arrange immediate accommodation. That support is ongoing, Mrs Ah Loo said.
It helped ensure the deportees had as soft a landing as possible, she said, and without it they would be much more likely to reoffend in New Zealand.
A spokesman for Justice Minister Amy Adams said the Government had been exploring options for "a cost effective and efficient system" for monitoring serious offenders deported to New Zealand.
"We recognise there's a gap and that's why we have a work programme underway to strengthen New Zealand's oversight of deported offenders which includes a register to track deported offenders, an information sharing agreement and law changes.
"At the moment there is no scheme for monitoring all offenders who are deported after completing their sentence overseas. Where Police are aware that an offender is to be deported, they make efforts to contact the offender to discuss their intentions on arrival, and will distribute that information to the relevant police districts."
The spokesman said it was the Government's intention that all deportees be subject to the same sort of conditions as they would be had their sentence been served in New Zealand.
About 200 New Zealanders are currently held in seven Australian detention centres, including on isolated Christmas Island, after a policy change last December to detain and deport non-Australians who have incurred a prison sentence of a year or more.
Labour has criticised the Government as much too slow to both lobby Australia on the issue, and to act on how to deal with the influx of criminals being deported to New Zealand.
Last month Justice Minister Amy Adams announced the signing of an information-sharing agreement with Australia that would provide more details on criminals being sent to New Zealand.
At the time, Ms Adams said the next step was to change the law to ensure prisoners arriving here would be subject to the same controls and supervision as they would be if they had served their sentence in New Zealand.
