The government should ban truckers from using cellphones while driving except in emergencies, transportation safety investigators said on Tuesday.

The National Transportation Safety Board (NTSB) recommendation came after it mostly blamed a fiery Kentucky crash last year that killed 11 people on the driver of a tractor trailer who was talking on his mobile phone.

Distracted driving is becoming increasingly prevalent, exacerbating the danger we encounter daily on our roadways, said Deborah Hersman, who chairs the safety board.

It can be especially lethal when the distracted driver is at the wheel of a vehicle that weighs 40 tons and travels at highway speeds.

In the Kentucky crash, investigators said the truck driven by Kenneth Laymon for Hester Inc crossed a median, broke through barriers and struck a van carrying 12 people in the early morning of March 26, 2010.

Laymon and 10 of the people in the van were killed.

The Freightliner was on a 700-mile (1,125-km) trip from Lansing, Michigan, to Cullman, Alabama.

Investigators said Laymon used his mobile phone for calls and text messages 69 times while driving in the 24-hour period prior to the crash.

This included four calls in the minute leading up to the accident, the final one coinciding with the time the 18-wheeler ran off the road at 5:14 a.m.

It was not clear whether the mobile phone was a hands-free device. Driver fatigue may have compounded the distraction, investigators said.

Transportation Secretary Ray LaHood has campaigned against distracted driving and last year his agency banned commercial truckers from sending text messages while at the wheel.

Transportation regulators have also proposed prohibiting hand-held cellphone use by truckers, and the NTSB recommendation is seen as an important endorsement.

Trucking groups support texting and cellphone bans but not any prohibition of hands-free devices. More than half of the 50 U.S. states ban texting while driving, while far fewer outlaw cellphone use.

(Reporting by John Crawley; Editing by John O'Callaghan)

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