A British culinary institution loved by expat Poms is disappearing from Kiwi shelves after a legal row over the name.

Supplies of Weetabix, long regarded as a staple of the British breakfast, are running out after Sanitarium wrote to the manufacturers saying it had New Zealand copyright on the terms Weetabix and Weet-Bix.

Sanitarium spokeswoman Kim Stirling said importing Weetabix to New Zealand was a trademark infringement on the company's brand.

"We're quite a big brand in New Zealand and they're quite a big brand in the UK. We feel it's quite an important thing just because we've built up the intellectual property [of Weet-Bix] here."

Stirling said if Weetabix was found on sale in a shop Sanitarium "would probably let them know our dismay".

Rachel Lane, co-owner of The English Corner Shop, in Auckland's Onehunga, said the company had been importing Weetabix for years and supplying local supermarkets. But a few months ago it also received a legal letter from Sanitarium.

"I've had a lot of heartbroken customers and really irate customers," said Lane.

Karen Blair, area manager for English food store Bramptins, said the Kiwi chain had not been approached by Sanitarium, but she was aware of the issue.

She said expats who had grown up with Weetabix would be upset if the product was no longer sold here. "It's a taste of home and it's something that you're used to."

Sanitarium has been trading in New Zealand since 1900 and started making Weet-Bix in 1932.

Weetabix was introduced to Britain by two South Africans who formed the Weetabix Food Company in 1932. The company declined to comment.