Lego has shown its first bricks made from recycled materials.

The basic 2 x 4 Lego bricks lack colour for now, but are made entirey from PET plastic derived from discarded bottles. They are the first 100 per cent recycled products to meet the company's quality and safety guidelines.

10 2 x 4 bricks can be made from a single one-litre plastic bottle.

Work on a recycled Lego brick has been underway for the last three years, with the toy brand testing more than 250 different variations of recycled plastics to get to this point.

"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," said Lego's vice president of environmental responsibility, Tim Brooks.

However, there is still some way to go before you'll find environmentally-friendly bricks in your Lego sets. Another year of tests are planned, and there's also the small matter of adding colours to the process.

"We're committed to playing our part in building a sustainable future for generations of children. We want our products to have a positive impact on the planet, not just with the play they inspire, but also with the materials we use," added Brooks.

"We still have a long way to go on our journey but are pleased with the progress we’re making."