Online retail spending was up a "respectable" 7 per cent in May, but annual growth has weakened, a BNZ report shows.
Compared with last year, when most months showed growth of 10 per cent or better, the underlying trend has been fairly flat since February this year.
Official interest rates started to rise in March and are expected to rise again this month, the fourth move this year, hitting the wallets of borrowers.
The BNZ report shows categories growing strongly in May included specialised food, computers and related gear and housewares.
Online spending at domestic sites was up 4.6 per cent on the same month last year.
That compared with official Statistics NZ figures for all electronic card spending in May, which was up 5.6 per cent for similar retail businesses.
BNZ said it was a little surprising that strong spending in physical stores was not reflected in the online sales figures.
But monthly figures could bounce up and down, so it was not drawing any conclusions yet.
However, the report also showed sales through overseas merchants were up 11 per cent on May last year.
Offshore purchases make up about 40 per cent of the online spending, with 60 per cent spent locally.
For the year to the end of March, online spending by rural New Zealanders shot up 20 per cent, much faster than the 14 per cent growth for city people.
And people in country areas are buying much more from overseas retailers, with spending up 27 per cent in the March year.
The BNZ report's measure of online spending is $2.8 billion for the year to the end of May. That figure excludes GST. The series includes key retailing, but not petrol, cars and the like. It also excludes food and motel and hotels, as well as airline tickets, movie tickets and contact lenses.
BNZ estimates $1.4b a year is spent on air travel, accommodation and car rentals