More people than ever are driving under the influence of their cell phones, according to a survey released Tuesday by the National Highway Traffic Safety Administration (search).

The survey showed 8 percent of drivers, or 1.2 million people, were using hand-held or hands-free cell phones during daylight hours last year, a 50 percent increase since 2002 and a 100 percent rise in four years.

All that talking is a potential safety issue, said NHTSA spokesman Rae Tyson.

"While we don't have hard evidence that there's been an increase in the number of crashes, we know that talking on the phone can degrade driver performance," Tyson said.

The District of Columbia and New Hampshire no longer allow talking on hand-held cell phones while driving, according to the Governors Highway Safety Association (search).

Some communities, such as Brookline, Mass., Santa Fe, N.M., and Lebanon, Pa., require hands-free cell phones, but about a half-dozen states prohibit local governments from restricting cell phone use in motor vehicles.

Young drivers, between 16 and 24, increased their talking on cell phones by 60 percent between 2002 and 2004.

The National Transportation Safety Board (search) said it wants all 50 states to ban those with learner's permits from using cell phones or other wireless devices while driving. New Jersey and Maine are the only two that have passed such laws.

The survey was conducted between June 7 and July 11, 2004, at 1,200 road sites across the country and, in some cases, supplemented by telephone surveys.