New Zealand imports around 10 million bunches of Californian table grapes each year and existing standards allow for no more than one live spider to be found per one million grape bunches.

While the number of spiders found was within this range, the environmentalist Green politicians have urged a ban.

"The reality is there's been significant public concern with respect to what risks the Black Widow spiders in grapes present and therefore we believe it is appropriate to review what the risks associated with the imports of these grapes are," O'Neil said.

The latest Black Widow spider was found at a supermarket in Nelson, at the top of the South Island, around 120 km (75 miles) west of Wellington.

Californian exporters are required to fumigate the grapes prior to shipment to kill spiders and other exotic pests.

The suspension would remain while a review examined the likelihood of Black Widow spiders becoming established in New Zealand and the resulting implications, which would probably take around six months, O'Neil added.

Forty-three containers carrying 66,608 boxes of Californian table grapes already on their way to New Zealand would be allowed into the country, but the Ministry of Agriculture said it would conduct additional checks.

Black Widow spiders have distinctive markings on their back and its bite can kill very young, elderly or debilitated people.