Lego has had to redraw plans to make its plastic bricks more environmentally friendly after using an alternative made from used plastic bottles generated higher emissions.
Recycled polyethylene terephthalate (RPET) was trialled as a replacement for oil, the current raw material for its bricks, but led to more carbon being generated.
Other materials were equally unsatisfactory, the company said.
“We tested hundreds and hundreds of materials. It's just not been possible to find a material like that," Lego chief executive Niels Christiansen told the Financial Times.
Lego has pledged to use only sustainable materials by the end of this decade but is struggling to find a material that gives the same colour, shine, feel and sound as oil-based plastic bricks, according to the report.