The company said its latest push to make its products less environmentally damaging was the first time it has used a recycled material which met the company’s strict quality and safety requirements.
However, despite the breakthrough, further testing is expected to last for over a year before the bricks appear in any new playsets.
Tim Brooks, the vice president of environmental responsibility at the Lego Group, said: “We are super excited about this breakthrough.
“The biggest challenge on our sustainability journey is rethinking and innovating new materials that are as durable, strong and high quality as our existing bricks, and fit with Lego elements made over the past 60 years.
“With this prototype we’re able to showcase the progress we’re making.”
The company said it already has a team of more than 150 people working to find and create sustainable solutions for Lego toys.
Over the past three years, the company’s scientists and engineers tested over 250 variations of PET materials and hundreds of other plastic formulations.
The new prototype is the result of that effort, which they said meets several of their quality, safety and play requirements – including clutch power.
The recycled plastic is made from polyethylene terephthalate (PET) sourced from suppliers in the United States.
On average, a one-litre plastic PET bottle provides enough raw material for ten of the classic 2x4 Lego bricks.
Mr Brooks said: “We know kids care about the environment and want us to make our products more sustainable. Even though it will be a while before they will be able to play with bricks made from recycled plastic, we want to let kids know we’re working on it and bring them along on the journey with us.
“Experimentation and failing is an important part of learning and innovation. Just as kids build, unbuild and rebuild with Lego bricks at home, we’re doing the same in our lab.”
He added: “We still have a long way to go on our journey but are pleased with the progress we’re making.”