The devices will be banned under a federal law that prohibits machine guns, according to a senior Justice Department official.

Bump stocks became a focal point of the national gun control debate after they were used in October 2017 when a man opened fired from his Las Vegas hotel suite into a crowd at a music concert below, killing 58 people in the deadliest mass shooting in modern US history.

The regulation, signed by acting attorney general Matthew Whitaker, will come into effect 90 days after it is formally published in the Federal Register, which is expected to happen on Friday, the Justice Department official said.

In March, President Donald Trump said his administration would "ban" the devices, which he said "turn legal weapons into illegal machines".

The amended regulations reverse a 2010 ATF decision that found bump stocks did not amount to machine guns and could not be regulated unless Congress changed existing firearms law or passed a new one.

After the Las Vegas shooting, there was a growing push by some members of Congress to ban bump stocks, but no legislation was passed. At least 10 states have sought their own restrictions on the devices.

People who own bump stocks will be required to either surrender them to the The Bureau of Alcohol, Tobacco, Firearms and Explosives or destroy them by late March, the official said.

The Gun Owners of America group said it would file a lawsuit against the Justice Department and ATF to protect gun owners from the "unconstitutional regulations".

Police said the gunman in the Las Vegas massacre, Stephen Paddock, fired for more than 10 minutes using multiple weapons outfitted with target scopes and bump stocks.

Paddock fatally shot himself after the massacre and there were 23 assault-style weapons, including 14 fitted with bump stock devices, strewn about the room near his body in his 32nd-floor hotel suite at the Mandalay Bay casino-hotel.

Australian Associated Press