A T-Mobile newspaper advert that implied a woman was using a BlackBerry while driving her car was irresponsible, the advertising watchdog ruled today.

The Advertising Standard Authority concluded that the ad breached its rules on responsible adverts and safety and has banned it.

T-Mobile was also reminded by the ASA that motorists can be prosecuted for not having proper control of a vehicle while using a hands-free phone in the car.

"Because the woman could be seen to be driving with only one hand on the steering wheel, consumers could infer that she was engaged in another activity while driving," the ASA ruled.

"We considered that, because motorists could be prosecuted for failing to have proper control when using a hands-free phone, the image of the woman was irresponsible and was likely to be seen to encourage dangerous practice."

The advert for T-Mobile's business solutions products showed a woman driving a car that had a glove box stuffed with office equipment, including a computer, under the headline "Work where you work best".

"Business data solutions from T-Mobile puts your business wherever you are. BlackBerry, Mobile broadband access and HotSpots mean the internet and email are always with you," the ad stated.

The advert ran in the London Evening Standard, the Guardian and the Times and prompted complaints that it was irresponsible and condoned dangerous driving because it suggested that a BlackBerry - a mobile device combining phone, internet and email access - could be used while driving.

T-Mobile denied the advert suggested its products should be used while driving.

The advert showed people that "their work could be fitted around" an everyday activity such as driving, the company told the ASA.

Another advert from the same T-Mobile campaign showed office equipment in a refrigerator and the company argued that consumers would not infer from this that they "should work in the kitchen".

"This advertisement was never meant to be about dangerous driving, but was about the general concept of rearranging your day to 'work where you work best' through the use of our suite of business devices," the company said.

· To contact the MediaGuardian newsdesk email editor@mediatheguardian.com or phone 020 7239 9857

· If you are writing a comment for publication, please mark clearly "for publication".