One of the UK’s biggest suppliers of toilet and kitchen roll has been stockpiling about 3.5m rolls in UK warehouses in preparation for a no-deal Brexit.

The German firm Wepa said it had been storing an extra 600 tonnes of toilet and kitchen roll in the last three to four months to safeguard supplies in Britain, in case the UK crashes out of the EU without an agreement on 29 March.

The company has also built six weeks’ supplies of the cardboard core used inside the rolls, as this cannot be sourced from the UK in sufficient quantities and is imported from EU countries in eastern Europe and Scandinavia.

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The firm has also decided to charter ships to take toilet and kitchen roll from a supplier in Naples to Swansea, rather than relying on trucks carrying its products via the Calais-Dover route.

Wepa is the latest company to unveil its preparations for a no-deal Brexit. Businesses ranging from car manufacturers to supermarkets and pharmaceutical firms have been stockpiling products and components as well as revising their supply routes. They fear that customs checks introduced after a no-deal Brexit would lead to lengthy delays and drive up the cost of materials.

Wepa’s UK managing director, Mike Docker, said: “The industry is pretty reliant on imports. We’ve been planning for Brexit since August last year to make sure we maintain our levels of service. What we’ve concentrated on is a hard Brexit. That’s the worst-case scenario for us, where we’d probably see major delays at the border.”

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The news, which was first reported by the BBC, comes a week after the chief executive of the supermarket chain Morrisons said its customers had begun stockpiling toilet roll and painkillers.

Wepa said demand for toilet and kitchen roll had gone up 7% in the past month, though this could also be affected by promotions in the supermarkets it supplies.

The company sells 80,000 tonnes of toilet and kitchen roll – 600m rolls – to the main UK supermarkets including Tesco, Sainsbury’s, Morrisons and the Co-op every year – a 10th of the total £1bn supply in Britain. Wepa is the biggest supplier of toilet and kitchen roll used by supermarkets for their own-brand products.