Refugees sit on the SIEV 358 asylum seeker boat after it capsized last year.
Immigration Minister Tony Burke says the government's PNG resettlement policy is working, despite recent boat arrivals including one in which five people are believed to have drowned on Tuesday.
''There is no doubt that it is having an impact,'' he told the ABC's Lateline program. ''Week on week there has been a trajectory downward [in the number of people arriving in Australia by boat].''
In the month since the government announced its radical plan to resettle all people who arrive by boat, more than 2500 asylum seekers have arrived.
A further 106 were rescued on Tuesday, after a vessel capsized near Christmas Island, with another five feared drowned.
''Some of the smuggling operations have tried to put together [. . .] a surge to overwhelm the system,'' Mr Burke said, while noting he had seen evidence that other asylum seekers were cancelling or delaying trips.
Mr Burke also defended the workability of the asylum policy, saying that arrivals would continue to be sent to PNG for resettlement, even if numbers remained high.
''We have an agreement that gets reviewed by Papua New Guinea and Australia after 12 months,'' he said.
But Mr Burke suggested that the strain on PNG might be eased by an ''increasingly significant'' number of asylum seekers preparing to return home of their own accord, instead of resettling in PNG.
He also said the government, if it were re-elected, would seek to broker agreements with countries other than PNG.
The government announced a plan to extend resettlements to Nauru earlier this month.
At an Indonesian conference on asylum seekers on Thursday, Papua New Guinea Minister for Foreign Affairs, Rimbink Pato, confirmed that Australia would get no asylum seekers back under his controversial deal with Mr Rudd.
This comes after PNG Prime Minister Peter O'Neill told Fairfax Media last weekend that he had not agreed to settle all asylum seekers who are found to be refugees after processing on Manus Island and that Australia would need to take back a share of them.
Mr Pato also told ABC Radio on Wednesday that about 50 Iranians had already agreed to return to their home country from PNG since the start of the new arrangement.
Mr Burke conceded on Tuesday that despite overall numbers dropping, people smugglers had recently put on a ''surge''.
Since Sunday, three boats carrying about 400 people have arrived, in addition to the boat that capsized on Tuesday.
''In the last few days, some of the smuggling operations have tried to put together a bit of a surge and to see if they can overwhelm the current system,'' Mr Burke told ABC television on Tuesday.
Tuesday's drownings began when the Australian Maritime Safety Authority received a request for help from a person on board the boat on Tuesday, about 120 nautical miles north of Christmas Island.
By 3.30pm, 106 people were recovered from the water. But at 6.30pm on Tuesday night AMSA called off the search.
The Australian Maritime Safety Authority said on Tuesday evening that the search for survivors had been called off after interviews with survivors that all survivors had been recovered.
''Information received from survivors indicates that up to five people remain unaccounted for. After an extensive search of the area for further survivors or bodies, none have been sighted, it is therefore believed any people unaccounted for have gone down with part of the vessel,'' a spokeswoman said.
HMAS Parramatta is taking the survivors to Christmas Island.
The deaths at sea come as the federal government faces a legal challenge to its resettlement plan, which it says would mean no asylum seekers who arrive in Australia by boat would be resettled here.
But Mr Burke said the legal terrain for that challenge was different to when the High Court struck down its plan to process refugees in Malaysia in 2011.
''After the Malaysia decision we changed the law for processing,'' he said on Monday. ''People have been processed under that new law.''
Tuesday's incident is the first boat tragedy since Labor announced its PNG plan in July.
It comes after two boat disasters last month, where a baby boy and four people died in two separate incidents. In June, 13 people died in another disaster.
The government has claimed that boat arrivals have fallen by as much as 30 per cent since the Papua New Guinea plan was announced, although a Fairfax Media analysis showed the drop was less than 20 per cent.