Shoppers in Britain have been warned they may struggle to find black tea on the shelves due to "supply issues" facing supermarkets, which are said to partially be linked to the disruption of shipments through the Red Sea.

One of the largest supermarket chains, Sainsbury’s, has cautioned shoppers in some stores that there are "nationwide" problems that could impact the availability of black tea.

But retail bosses have said the problems are "temporary" and stressed that the impact on consumers is expected to be "minimal."

A sign in one Sainsbury’s store read: "We are experiencing supply issues affecting the nationwide supply of black tea. We apologize for any inconvenience and hope to be back in full supply soon."

Sainsbury’s has been contacted for comment.

It is understood that the supply problems, which are partly linked to the disruption of shipments through the Red Sea, are specifically linked to just one supermarket tea supplier.

Andrew Opie, director of food and sustainability at the British Retail Consortium (BRC), said, "There is temporary disruption to some black tea lines, but the impact on consumers will be minimal as retailers are not expecting significant challenges."

Tea is largely produced in Asia and East Africa, with China, India, Sri Lanka and Kenya producing around three-quarters of tea globally.

Freight shipments from these regions have faced major disruption over the past two months due to attacks in the Red Sea.

Attacks on ships by Houthi rebels, which they said were in solidarity with Palestinians due to the ongoing assault of Israeli forces on the Gaza Strip that left thousands killed, caused most shipping firms to avoid using the key trade route. The alternate route heads toward the Suez Canal, redirecting shipments around the Cape of Good Hope at the foot of Africa.

This adds roughly 10 to 14 days to shipment times, as well as increased costs for shipping firms.

Sparsh Agarwal, owner of several tea gardens in Darjeeling, India, and founder of Dorje Teas, told the i newspaper in December that tea shipments were being stalled due to the disruption.

"We sent shipments to the U.S. and Europe two weeks ago, but they are still in Bombay port and have not been picked up yet," he told the newspaper at the time.