Drivers caught using a cellphone without a hands-free kit could have their device impounded for up to 24 hours - even if they are a first-time offender.

Cape Town traffic bylaw 2011, to be implemented next month, is aimed at improving traffic safety and this includes getting motorists to chat only legally on cellphones.

JP Smith, a member of the mayoral committee for safety and security, said distracted driving - which includes talking or sending SMSes on cellphones while at the wheel - along with speeding, drunken driving and not wearing a safety belt were the major causes of death on the roads.

Smith said between 3000 and 8000 fines were issued each month to motorists caught using a cellphone while driving.

"What is clear is that the fines are not changing driving behaviour," said Smith.

Canvassing international best practice, the mayoral committee consulted traffic experts such as the California Highway Patrol, which said the best safety intervention was the introduction of effective legislation.

"Before you fight for more traffic-enforcement personnel, change your laws so that it's easier to do your work," the experts said.

"In Cape Town - and South Africa as a whole - that means creating a greater, and constant, disincentive to break the laws," Smith said.