The Toys R Us chain is being sued over allegations it stole one of its former partners’ trade secrets to develop its own tablet computer.

Fuhu – the Los Angeles based creator of the Nabi tablet – claims the toy chain copied the design, user-experience and online services of its device.

Toys R Us used to have exclusive rights to sell Fuhu’s machine in the US, but this deal has since lapsed.

A spokeswoman for Toys R Us was unable to comment at this time.

Fuhu is part-owned by the Taiwanese computer-maker Acer, the gadget manufacturer Foxconn and the memory chip producer Kingston.

Fuhu, the creator of the Nabi tablet, claims Toys R Us copied the design for its new tablet Tabeo

It began life as an internet software provider before shifting into the tablet market in November 2011, when it announced it would be selling the Nabi through the Toys R Us and Babies R Us chains in the US.

The machine came pre-installed with popular games including Angry Birds and Fruit Ninja as well as an educational maths-learning program and a painting app.

At the time, a Toys R Us executive said he expected the device to “be a hit with our customers” in the run-up to Christmas.

It also received positive reviews from Time and Wired magazines, among others.

But Fuhu alleges the chain subsequently did “virtually no promotion” and only sold about 20,000 units over the period because it had not ordered more.

Child-targeted tablets proved to be one of the season’s hot categories with rival devices – including the LeapPad Explorer Tablet and the VTech Innotab – selling out in the run up to the holiday.

In January 2012 Fuhu and Toys R Us ended their exclusive agreement.

Eight months later the store announced it would sell its own Android-powered hand-held – the Tabeo – in the US from October.

The announcement followed in the footsteps of another retailer, Amazon, which had seen its own-branded device become a best-seller.

Fuhu claims the Tabeo copied the butterfly-shaped bumper used to protect the Nabi, the device’s software eco-system and the firm’s “business blueprint” in order to release a product ahead of Christmas this year.

“We created a highly innovative product,” said Robb Rujioka, Fuhu’s co-founder.

“Cheap knock-offs will devalue our brand and the children’s tablet category as a whole.”

Fuhu is now demanding all Tabeos be turned over to it as well as unspecified monetary damages.

It has also launched a successor to its original product with improved specifications, which is sold via other retailers.