SAN FRANCISCO (AFP) - A pair of US inventors are bringing to market a computerized car key that prevents people from chatting on mobile telephones or sending text messages while driving.

Key2SafeDriving adds to a trend of using technology to thwart speeding, drunken driving, and other risky behavior proven to ramp-up the odds of crashing.

Once slipped into a car's ignition, the key created by US university researcher Xuesong Zhou and Dr. Wallace Curry sends a wireless signal to a driver's mobile phone blocking calls or texting.

"If you're in driving mode, you can't talk or text -- period," a character tells a friend trying in vain to send a text message while driving a car in a YouTube video demonstrating how the keys work.

The keys are being pitched as a way for parents to stop teenage children from focusing attention on beloved mobile telephones instead of traffic.

A growing number US states are enacting laws against teenagers using mobile telephones while driving.

Traffic statistics support arguments that mobile telephones are on par with alcohol use when it comes to hurting judgment and reaction times of drivers.

In October, Ford Motor Co. unveiled a "MyKey" device which allows parents to control how fast their teenagers drive, limits the volume on the car radio and makes sure their seat belts are fastened.

Ford said that it will be a standard feature starting next year on the 2010 Ford Focus and other Ford, Lincoln and Mercury models.

Global Positioning System devices have been on the market for some time which allow parents to monitor the every move of their teenage driver.

Technology used to thwart drunken driving includes preventing car engines from starting until aspiring motorists have passed dashboard breath-alcohol tests or reaction-time tests on mobile phones.