WASHINGTON—Laws that forbid motorists from using hand-held phones or texting while driving don't appear to result in a significant decrease in vehicle crashes, according to a new study by the Highway Loss Data Institute expected to be released Friday.

The study, expected to be released at a conference in Washington, D.C., Friday, comes amid stepped-up efforts by federal highway-safety regulators to ban texting while driving and curb other forms of driver distraction. Transportation Secretary Ray LaHood earlier this week announced rules to forbid commercial truck and bus drivers from text messaging while driving. Mr. LaHood has said he would ban all texting while driving if he could.

The Transportation Department in a statement Friday criticized the HLDI findings, saying "it is irresponsible to suggest that laws banning cell phone use while driving have zero effect on the number of crashes on our nation's roadways. A University of Utah study shows that using a cell phone while driving can be just as dangerous and deadly as driving drunk. We know that by enacting and enforcing tough laws, states have reduced the number of crashes leading to injuries and fatalities."

The HLDI, a research organization sponsored by the insurance industry, studied data on monthly collision claims in four states that banned the use of hand-held phones by motorists before and after the bans went into effect. The HLDI also compared collision data from states that enacted bans on driving while texting or phoning to accident claims in states that didn't enact such bans.

In New York, HLDI said its researchers found that collision claims decreased compared to other states, but the decrease began before the state's ban on hand-held phoning took effect.