Motoring groups say Apple's smartwatch could be dangerous for drivers and could lead to more road deaths.
The head of policy and research at Britain's Institute of Advanced Motorists, Neil Greig, said: "An iWatch has the potential to be as distracting as any other smartphone device - more so if you have to take your hand off the wheel and your eyes off the road to interact with it."
The Apple Watch, which has a screen measuring 38mm by 42mm, also sends users small vibrations.
Mr Grieg said: "There is no need for a change in the law, but more a change in enforcement.
"There are not enough officers and people need to be aware. People don't think they are going to get caught."
Research by IAM on smartphone use in the UK between 2006 and 2010 claimed distraction from a mobile device was a contributory factor in 1960 road accidents which resulted in injuries. The figure included 110 fatal accidents.
"An iWatch is like a smartphone," Mr Grieg said. "Therefore our previous research is applicable to this new product."
A UK Department of Transport spokesman said drivers caught using the device behind the wheel would face the same penalties as those caught using mobile phones.
"The fact that the device is attached to your wrists does not matter," he said.
Because the new device was similar to a mobile phone, police would have a verifiable "paper trail" that could be used to convict offenders.
Drivers caught using a hand-held mobile phone face a penalty of three licence penalty points and a £100 ($201) fine. If the use causes a fatal accident, the penalty is up to two years in jail.
The spokesman continued: "The onus is on the driver to find out - not knowing it's an offence is not an excuse.
"I'm sure people will be caught," he said. "You can only warn people and hope they listen."
The Apple watches were announced this month. They will be available from next year, and in Britain will cost about £300.
Apple did not respond to requests for comment.