Westpac Banking Corp in New Zealand has announced it will not take any new loan applications from property investors who do not have a 40 per cent deposit from 4.30pm on Wednesday, some six weeks earlier than required by the NZ Reserve Bank.

The central bank on Tuesday said it intends have the new lending restrictions in force by September 1 and asked lenders to comply with the spirit of the new regulations immediately.

In a statement, Westpac said the timelines were "a shorter transition period allowed than in 2013 and 2015, when there was a six month period to make all the necessary adjustments and comply".

The RBNZ plans to extend mortgage lending restrictions on Auckland property investors to the rest of the country, making them more onerous by requiring a bigger deposit and reintroducing a uniform national cap on highly leveraged owner-occupier mortgages.

"LVR restrictions to date have improved the resilience of bank balance sheets by reducing banks' exposure to riskier mortgages," governor Graeme Wheeler said on Monday.

"This policy initiative is intended to further improve the resilience of bank balance sheets, and it will assist in restraining credit and housing demand."