The services will be made available to mobile users at a later date

Vodafone will sell a plug-in card to bring laptop PC users high-speed data on the move, in an initiative initially confined to corporate clients.

The service, which will be restricted to business users in London and the M4 corridor at first, will be rolled out to major UK cities by April.

It will take on Hutchison-owned 3, the other firm offering services in the UK.

However, Vodafone has not revealed when the service will be offered to mobile phone users.

The Connect 3G/GPRS datacard integrates 3G and GPRS functions, enabling transmission at speeds of up to 384 kbps.

Handset problems

Hutchison launched the 3 network in March 2003, but in the first six months signed up only 155,000 people.

There were also complaints that the network was not wide enough, and problems with handset supply caused by testing delays at Japanese firm NEC.

Some analysts have expressed scepticism that there is mass consumer demand for the new 3G services, which include speedy emails and data transfer.

Vodafone hopes to overcome these difficulties, by targeting the users they already have in the business sector, and whose needs they are familiar with.

The move also allows the opportunity to fine-tune any teething problems with service delivery or handsets, before offering 3G to the general public.

Vodafone chief marketing officer Peter Bamford said: "3G will enable us to drive more mobile minutes, deliver high quality content and entertainment, and enable greater productivity for mobilising business."

Vodafone's 3G networks have already been launched in Italy and Germany,