British exporters have been warned they could lose billions of pounds worth of business, with over six in 10 European companies that work with UK businesses hinting they are likely to turn to firms within the single market after Brexit.

According to figures released by the Chartered Institute of Procurement & Supply (CIPS) on Monday (6 November), 63% of the EU firms polled last month revealed plans to move their part of their supply chains away from the UK, following Britain's decision to leave the single market and the customs union.

The figure marks a sharp increase from May, when a similar survey found the number of companies planning to switch part of their operations to EU countries stood at 44%.

However, it is not only EU businesses which are drawing up plans to switch suppliers, with 40% of the UK businesses polled among 1,118 supply chain managers in the UK and Europe, revealing they had begun looking for domestic suppliers to replace their current EU partners.

Again, the figure is higher than the 30% recorded by a similar poll five months ago.

Since Britain voted in favour of leaving the 28-country bloc in June 2016, pro-EU campaigners, both within Westminster and the business world, have warned the decision will result in a sharp decline in trade with members of the single market.

"The Brexit negotiating teams promise that progress will be made soon, but it is already too late for scores of businesses who look like they will be deserted by their European partners," said Gerry Walsh, the chief executive of CIPS.

"British businesses simply cannot put their suppliers and customers on hold while the negotiators get their act together."

"Despite a formal separation still being some time away, 8% of UK businesses said their organisation has already lost contracts as a result of Brexit with 14% believing part or all of their organisation's operations will no longer be viable."

The report comes on the same day as the president of the Confederation of British Industry (CBI) warned the majority of UK firms will begin moving staff and delay investment by March next year if no Brexit transition deal in place.

Speaking at the annual lobby group's conference in London, Paul Drechsler said a poll of 306 companies by the CBI revealed that a quarter will trigger contingency plans by January if there is no transition deal in place, while a further quarter said they would wait until March.

One in 10 businesses said they had already implemented – or were in the process of implementing – contingency plans.

"We must leave behind the episodic approach and take this opportunity to move forward as one – business and politicians, here and abroad," he said.

"Brexit is only 508 days away. But for many businesses, their alarm clocks are set even earlier than that. They're set to the moment they will actually enact their contingency plans."

"So government and the EU need to get a move on. Making progress, remaining flexible and, first of all, sorting out transitional arrangements."