A US gun maker has triggered controversy by selling a kit that makes a real Glock pistol look like a children's Lego toy gun, at a time when hundreds of kids are falling victim to shootings.

The Danish manufacturer of the building blocks has sent the Utah-based company, Culper Precision, a demand to stop producing the red, blue and yellow covering for handguns.

"Our organisation reached out to Lego, which then sent a cease and desist letter to the reckless gun maker," said Shannon Watts, founder of the US group Moms Demand Action, which advocates stricter gun controls.

The colourful brick design gives the semi-automatic weapon a strong resemblance to a Lego toy. The gun maker was marketing it as a "Block19" which sold for between $549 and $765.

"Here's one of those childhood dreams come to life," said Culper Precision in an advert for the gun on Instagram posted on 24 June.

"Guns are fun. Shooting is fun. 30 rounds full auto is fun," the company said on its website.

Ms Watts, who stressed that "unintentional shootings have risen by 30% in the past year," told the Washington Post her first reaction upon seeing the gun was that it was "sick and children would die."

She said that in 2021 there had been more than 165 accidental shootings by children in the US, according to the organisation Everytown.

Last year 142 people died as a result of accidental discharges by children or minors, the same group said.

Culper Precision's CEO Brandon Scott confirmed to the Washington Post that he had received Lego's formal notice and said the company had decided to comply, after having sold fewer than 20 of the items.

In a statement on its Instagram site, the company said it was "grateful for the attention that Block19 is currently getting across the globe".

It continued: "We built Block19 to create an opportunity to talk about the enjoyment of the shooting sports and the joy that can only be found in marksmanship practice and training."

Culper Precision said it "would remind everyone that failing to secure a firearm of ANY colour from unauthorised persons is irresponsible".

The statement added: "Our business is taking a firearm of known value and transforming it into a personalised invaluable treasure for a fair price.

"People have the right to customise their property to make it look like whatever they want."