Criminal gangs across the world are pursuing a new, lucrative and almost untraceable commodity - Lego.

Sets of the plastic bricks can sell for thousands of dollars on online trading sites, prompting thieves to target toy shops from America to Australia.

The trend came to light this month when US police revealed back-to-back cases in New York state and Arizona worth almost US$300,000 ($358,000).

Caleb Raff, who runs the Brick Hutt Lego shop in Santa Rosa, California, said he knew of several thefts near his store.


Raff, who earlier this year sold a single piece for US$15,000 - the Platinum Avohkii Mask of Light - said criminals seemed to be getting wind of the collectability of some sets.

"If you look at other makes - Kenner, Hasbro, Fisher Price, those have always been collectable," he said. "With Lego, it's a new trend and if you know what to get then there's value."

Lego's popularity is surging after years of crisis saw the Danish family business turned over to new management. Tie-ins with films, such as the Star Wars and Harry Potter series, have helped it connect with a new generation of children.

Expensive specialist kits include Tower Bridge or the Ewok village, from Return of the Jedi, which sell for 150 ($297).

Prices can rise much higher for unopened, discontinued lines, such as a 2899-piece Statue of Liberty, released in 2000, which now sells for 6000.