The organisers behind New Zealand's inaugural Click Monday promotion have hit back at a marketing expert who says it may not be the best way for buyers to nab bargains.

The 24-hour pre-Christmas sale is offering discounts to online shoppers who can click through to retailers' websites to make purchases.

More than 80 retailers are taking part, including Pumpkin Patch, Ezibuy, Hallensteins, Fishpond, Pascoes, Bendon, Icebreaker, Macpac and Toyworld.

The promotion is the first attempt in New Zealand to emulate a popular event in the United States known as Cyber Monday, which has spread to Australia and China.

Click Monday continues until 7pm tonight but Associate Professor Ekant Veer of the University of Canterbury said the site's ''enticing'' sales were not necessarily the best deals.

Veer said ''savvy buyers'' were finding out that some of the items for sale were cheaper at other times of the year.

Others were not ''the current trendy products, but . . . old lines and out of date products'', he said.

''Click Monday is more akin to excitement and mob mentality associated with purchasing behaviour, rather than rational savings behaviour.''

Click Monday was co-organised by Blackpepper Interactive owner Alain Russell and Auckland e-commerce consultant Cate Bryant.

Bryant said it was ''somewhat misleading'' for Veer to say the site was offering old lines and out of date products, as ''the new Apple iPad Air or all of the new season apparel clearly contradict this statement''.

''We also didn't exempt retailers from wanting to clear some product at prices that are attractive to consumers - that would mean consumers would miss out,'' she said.

''Consumers certainly voted with their wallets, so the price points must have been competitive enough for them to purchase. Retailers were taking a punt on the first ever event of this kind of any scale in New Zealand and those that provided great offers have had a great result.''

Bryant said the Click Monday site had sent more than 150,000 clicks through to retailers by 11pm last night. It had 62,000 visitors in that time, generating 20 million hits.

''We're pretty delighted. It's not a bad start. The sheer amount of traffic has slowed down quite a few retailer sites - some pretty much to a stop, which will have unfortunately dampened sales.''