WASHINGTON - Cellphone use is a factor in far more fatal crashes than anyone realized, according to a report released Tuesday by the National Safety Council.

The council estimated that 25 percent of all crashes involved cellphone use. The Governors Highway Safety Association disputed that estimate, noting the federal figures suggest distraction is a factor in just 10 percent of fatal crashes and cellphones are implicated in just over 1 percent of those.

But the safety council found that even when drivers said they were using their cellphones at the time of a crash that admission was not recorded in accident reports compiled for use in the national debate on distracted driving.

"We believe the number of crashes involving cellphone use is much greater than what is being reported," said Janet Froetscher, the council's president. "Many factors, from drivers' not admitting cellphone use, to a lack of consistency in crash reports being used to collect data at the scene, make it very challenging to determine an accurate number."

Researchers reviewed 180 fatal crashes over a three-year period where there was evidence that the driver was using a cellphone. In one of those years, 2011, only 52 percent of the crashes were recorded in the national database as cellphone-related.

The report also found wide variation among states in their reporting of fatal crashes as cellphone-related.

"The public should be aware that cellphone-involved fatal crashes are not accurately being reported," said Bill Windsor, associate vice president at Nationwide Mutual Insurance Company, which helped fund the study. "These statistics influence national prevention priorities, funding decisions, ... legislation and policy, even vehicle and roadway engineering."

The National Transportation Safety Board called in 2011 for a ban on all cellphone use while driving.