"This is John Key's legacy. After four years of National, the only way people can close the wage gap with Australia is to move there. This Government is turning New Zealand into a finishing school for future Australians."
Mr Key said Mr Shearer's "stunt" was hypocritical. He rejected any suggestion the failure to stem the exodus was a failure, saying figures for net migration were "fairly similar" under Labour.
Statistics NZ figures show that in the year ending October 2008 - Labour's last year in Government - there was a net loss of 34,600 people to Australia compared with 39,300 for the year ending October 2012.
About 53,700 people moved to Australia over the past year and 14,400 came the other way, compared with 47,800 people who went to Australia long term in the year to October 2008, while 13,200 came back the other way.
Mr Key said it was inevitable Australia would have an attraction, given the high wages paid, such as in the mining sector.
"So yep, we have got to do better in that regard, but I don't think you are going to stop people going when there are such huge amounts of wages being paid."
Mr Shearer said he was confident the stunt would not backfire on him as it did on Mr Key, saying, as Mr Key did in 2008, that his party could deliver reasons to stay in New Zealand.
"We believe we can bring the numbers down. We certainly will put in policies that will give people hope to stay here in New Zealand."
He said he would not set a specific target on migration.
However, his party would offer "opportunities" such as a high-wage economy, affordable housing and initiatives for companies.
"What we need to be able to do is put our hands on the wheel and say our companies need assistance, they need support and if they get support they will employ more people and we'll have more jobs and better paid jobs."
He also had advice for Mr Key in the 2014 election: book out the much larger Eden Park for the campaign video on transtasman migration.
