Online spending at international merchants was up 12 per cent compared to April last year with computer, clothing and entertainment media contributing to more than 60 per cent of growth in spending at international online retailers.
New Zealand's annual online retail spending is now worth $4.3 billion, the equivalent of 7.7 per cent of all retail sales, according to Statistics NZ.
BNZ research director Gary Baker said April's increase in online spending was a strong result.
"The 16 per cent year-on-year increase at domestic sites for April is a strong result, given recent months have been averaging around the 10 per cent mark," Baker said.
"While the figure reflects a strong month, there is no basis at this stage to suggest a change in trend," he said.
"Monthly retail spending is traditionally quite volatile."
Food is a major category for online sales and had been for "some time", Baker said.
First Retail Group managing director Chris Wilkinson said the jump in local online spending in April reaffirmed Kiwis demand for convenience, range and affordability - key factors influencing Kiwis preference for shopping online.
"The past year has shown increasingly busier lifestyles and a growing priority for family and leisure time are pushing people towards e-commerce," Wilkinson said.
"New Zealand businesses are lifting their game online rapidly, many as a consequence of greater online competition that was heralded by Amazon's Australasian launch."
Wilkinson said the growth in online retail sales showed local brands and retailers were increasingly becoming a priority for consumers.
Online spending in the month of March was unusually slow, largely due to weak growth in purchases from overseas websites.
Spending at domestic sites in March was up just 7 per cent, in line with the growth in spending at local bricks-and-mortar stores, and online spending at international merchants was up just 2 per cent.
