US president Donald Trump has said he is consulting with the National Rifle Association (NRA) over whether it makes sense for a Texas company to publish downloadable blueprints for a 3D-printed gun.

Mr Trump tweeted he is "looking into 3D Plastic Guns being sold to the public," adding that he "already spoke to NRA".

The president expressed doubt, saying the move "doesn't seem to make much sense!"

He spoke after eight states filed suit against the administration, contending the hard-to-trace plastic weapons are a boon to terrorists and criminals and a threat to public safety.

The suit, filed in Seattle, asks a judge to block the federal government's late June settlement with Defense Distributed, which allowed the company to make the plans available online.