Nearly two thirds of EU businesses expect to move some of their supply chains out of the UK because of Brexit, a new survey has found.
The research by the UK's Chartered Institute of Procurement and Supply (CIPS) also found that 40% of UK firms are looking to replace their EU suppliers.
The survey of 1,118 supply chain managers in the UK and Europe found that the number of EU firms planning to shift part of their supply chain out of Britain has risen to 63% from 44% in May.
CIPS also reported that 25% of UK businesses with more than 250 employees have spent more than £100,000 preparing their supply chains for Brexit.
The survey found that 64% of UK businesses are suffering extra costs as a result of currency fluctuation, 20% are struggling to secure contracts that run until after the Brexit date of March 2019, and 20% have postponed or cancelled contracts due uncertainty.
Nearly one in 10 UK firms, 8%, 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, according to the study.
Gerry Walsh, CIPS group CEO, said firms needed more clarity from the Brexit divorce talks between the UK and EU.
"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.
"British businesses simply cannot put their suppliers and customers on hold while the negotiators get their act together.
"While the TV cameras are fixed on Brussels, the deals which will determine the future prosperity of Britain and Europe are being struck behind closed doors in businesses large and small. The lack of clarity coming from both sides is already shaping the British economy of the future - and it does not fill businesses with confidence.
"The success of the negotiations should not be measured on the final deal only, but on how quickly both sides can provide certainty. The clock is ticking."
The survey classed EU businesses as European firms with UK supply chains, of which there were 106 in the tally.