Marijuana use has not been found to increase the risk of car crashes, according to a new federal report.

Studying car accidents in Virginia Beach, Va., during a 20-month period ending in 2012, researchers randomly sampled 3,000 accident-involved drivers and found no evidence suggesting those with marijuana in their system were more prone to accidents, according to a National Highway Traffic Safety Administration report released Friday.

When researchers controlled for factors such as age and gender, they found no evidence marijuana use increases accident risks. This was despite the fact that, in the study, drivers who tested positive for marijuana use happened to be involved in more accidents.

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By comparison, the study found drivers with breath alcohol of .08 to be about four times more likely than sober drivers to be involved in accidents. Those nearly double the legal limit, at .15, were 12 times more likely to crash.

The study is billed as the largest ever conducted to assess the relative crash risk of drivers who consume alcohol compared to pot.

Officials contend more research must be conducted in the wake of recreational pot legalization in Colorado, Oregon, Alaska and Washington state.

“Drivers should never get behind the wheel impaired, and we know that marijuana impairs judgment, reaction times and awareness,” NHTSA associate administrator for research and program development Jeff Michael said in a statement.

“These findings highlight the importance of research to better understand how marijuana use affects drivers so states and communities can craft the best safety policies," Michael added.

Correlation between pot use and crashes is of considerable interest as fewer people drive under the influence of alcohol and more drive under the influence of marijuana, according to another study released Friday by the NHTSA.

That study found that the number of nighttime weekend drivers with marijuana in their system grew by 48 percent, from 8.6 percent in 2007 to 12.6 percent in 2013-2014. During the same period, the number of drivers with alcohol in their system dropped nearly a third.