"There are teething problems with 3G phones and coverage, so we recommend sticking with a 2G phone for the time being," said Malcolm Coles, editor of Which? Magazine. "We'll be keeping an eye on 3G phones over the coming months to see if they, and the networks, live up to their hype."
Which? also criticised the phones, which have colour screens, video and picture messaging or internet browsers, for the bulkiness of the handsets.
The announcement has angered 3G providers who were hoping that a Christmas rush would help recover some of the £22.5 billion they spent on 3G licences.
Speaking to the BBC, Edward Brewster, head of external relations at 3 Mobile, said that Which? was displaying a "lack of understanding" of the 3G market. He says 80% of people in Britain can access 3 Mobile's video services, while 99% can access its voice services.