The US Department of Justice on Saturday moved to ban bump stocks, firearm accessories used to mimic automatic fire.

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In a notice submitted for approval to the Office of Management and Budget, the DoJ proposed that bump stocks be included in the definition of “machine gun” in the 1934 National Firearms Act.

The accessory was not used in the recent Florida school shooting, in which 17 people were killed, but it was used last year in the deadly shooting in Las Vegas.

Officials said the Las Vegas gunman had 12 rifles fitted with bump stocks in the hotel room where he carried out the attack that left 58 dead and more than 850 injured.

Donald Trump vowed last month to ban bump stocks and other attachments that enable semi-automatic firearms to fire at close to the rate of a machine gun.

“President Trump is absolutely committed to ensuring the safety and security of every American and he has directed us to propose a regulation addressing bump stocks,” attorney general Jeff Sessions said in a statement.

The NRA, which donated $30m to Trump’s 2016 presidential campaign, has not supported an outright ban on bump stocks.

The gun lobby group does support additional regulations for bump stocks and did not immediately respond to a request for comment.

On Friday, the NRA filed a lawsuit hours after Florida governor Rick Scott signed into law new gun regulations, including a bump stock ban.