Buyers may find credit conditions are quite different to what they were when they first signed a contract to buy an apartment.

Lending restrictions could make it tougher for developers to sell newly-built apartments.

Sources say bankers are increasingly worried about "settlement risk" to developers – the risk that people who have bought properties off-plans, with the intention of settling when the development is complete, will now not be able to do so.

Data from Colliers shows that a record number of apartments are due to be completed over the coming years. There are 2770 set to come on to the market in Auckland alone this year, the highest number since 2005.

MARTIN DE RUYTER/STUFF Apartment buildings are being built around the country but the exuberance of a year ago has left the market, in many places.

Another 3840 should be finished next year.

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Mortgage broker John Bolton, of Squirrel, said there was an emerging issue of whether buyers would be able to go through with deals.

SEAN GALLUP/GETTY A record number of apartments are due for completion over the next couple of years.

"If people were buying off-plans two years ago... the world was very different two years ago to what it is now."

Some buyers could have been off-shore buyers who were reliant on foreign income to service their loans, which is now not allowed by banks, he said.

Others could be investors who would be affected by the new loan-to-value restrictions, which require a 40 per cent deposit on investment properties. He said some buyers would be speculators who had planned to on-sell the property for a capital gain without settling.

Even if someone met the banks' lending criteria at the time they paid a deposit on a property and pledged to buy it, that did not mean that they would now, he said.

Most pre-approvals are only valid for three months, and six at the outside. But it can take years for a property development to finish.

Banks were also now tougher about servicing, he said, and wanted to see that people could afford their mortgages if rates returned to 8 per cent.

Developers were increasingly at risk of not being able to sell apartments for the amounts they thought they could get, or as quickly as they had hoped, he said.

"This isn't unlike the GFC," Bolton said. "A similar sort of thing happened in 2008 and 2009, but the industry managed their way out of it. Fundamentally, there is a shortage of property – we're not building enough – so this is a short-term issue but it highlights the challenges developers face in a market with tight credit conditions."

Market analyst Rodney Dickens said it had been a concern in Australia, where foreign investors had walked away from deposits they had put down on apartments bought off plans.

Property website Realestate.co.nz reported in June that the number of apartments listed for sale was the highest it had been in a decade.

Banks approached for this story did not want to comment.