The company behind Squishmallows, the squidgy pillows-with-a-face that count Lady Gaga and Kim Kardashian among their fans, has filed a lawsuit against Build-A-Bear over claims it has produced a “knock-off” to cash in on its success.

Jazwares, which Warren Buffett’s Berkshire Hathaway acquired two years ago as Squishmallows became a global TikTok sensation, said that Build-A-Bear Workshop’s new Skoosherz toys look too similar to its own plush, huggable toy.

Build-A-Bear, which launched the Skoosherz line last month in the run-up to Valentine’s Day, struck back immediately with its own legal action claiming that its £18 cuddly pillow-like toys-with-faces are an extension of its existing animal range.

The company argued that the Skoosherz line is only the most recent type of “soft, pillow-like squishie-type” toys that have been available for years.

Build-A-Bear, which has filed its legal action in Missouri, wants a court declaration that it has not infringed Jazwares’ “trade dress” rights in Squishmallows, and that any such rights are unenforceable.

Jazwares, of which Berkshire Hathaway took control in a $12bn deal for its parent company Alleghany in October 2022, has filed its intellectual property lawsuit in California.

The company launched Squishmallows in 2017 and has vigorously defended its copyright since the toys became a global bestseller after going viral on TikTok. It called the Skoosherz toys “knock-offs”.

Jazwares said in its lawsuit that rival toys were similarly “shaped fanciful renditions” of animals, with “simplified Asian-style kawaii faces” and “velvety velour-like” fabric. Kawaii means cute, tiny and lovable in Japanese.

The new Skoosherz toy range includes a strawberry cow, rainbow sparkle teddy bear and red raptor.

There was also a range of Squishmallows animals including a cat, frog and fox – they also come as fruit, vegetable or a hybrid cross – which became the must-have Christmas present in 2022. There are now more than 1,000 versions available.

“Build-A-Bear has gone to great lengths to copy the distinct look, feel and tactile design to capitalise on Squishmallows’ global success blatantly and intentionally,” the company said.

Jazwares has already launched a legal action against the Chinese online retailer Alibaba for allegedly selling counterfeits.

“When it comes to intellectual property rights imitation is not the sincerest form of flattery,” said Moez Kaba, lawyer for Jazwares.

Build-A-Bear Workshop was founded in 1997 by Maxine Clark, who was inspired to launch her own company after going on a shopping trip with a friend’s daughter. After being unable to find a Beanie Baby, the 10-year-old said they could make the toy at home.

The first store was opened in St Louis, Missouri, and the business, which described itself as a “teddy-bear themed retail-entertainment experience”, has expanded to more than 400 locations in 19 countries.

The company, which has a market value of $322m, owns and operates about 350 stores with a further 68 franchised outlets operating internationally.

Consumers have the option of customising their chosen furry animal as an activity in-store, or online, or can be bought without accessories.

Build-A-Bear did not respond to a request for comment.