Laws that ban texting while driving have not reduced the number of crashes across four states in the US according to a study, but a slight increase in road accidents has been recorded.

The Highway Loss Data Institute compared the insurance claims in four states of California, Louisiana, Minnesota and Washington before and after the texting ban, with those in nearby states that don’t have these laws.

After the bans, crash patterns varied from 1% more crashes in Washington to about 9% more in Minnesota, and the largest crash increase (12%) after the texting ban was among young drivers in California.

The researchers have calculated rates of collision claims for vehicles up to nine years old during the months before and after driver texting was banned.

The study shows crashes have increased in three states after the bans were enacted, which indicates that bans could increase the risk of crashing for drivers who continue to text despite the laws.

The study notes noncompliance as the key reason for the increase in crashes as young drivers among 18-24 years are most likely to text with 45% saying they do so in states that ban texting.

It pointed out that the bans are ineffective as 48% of drivers admitted to texting in states without bans.