Aerospace firm Airbus, which makes wings in Flintshire, has warned it could pull out of the UK with the loss of thousands of jobs if there's a "no-deal" Brexit.
The firm, which employs over five thousand at Broughton, says it would "reconsider its investments in the UK, and its long-term footprint in the country" if Britain crashed out of the single market and customs union without a transition agreement.
Publishing a Brexit 'risk assessment' on its website, the firm also called on the Government to extend the planned transition period due to run until December 2020 if a deal is agreed, saying it was too short for the business to reorganise its supply chain.
If there was no extension it would "carefully monitor any new investments in the UK and refrain from extending the UK suppliers/partners base", it said.
The Welsh Government said the announcement is worrying.
Meanwhile, Conservative MP Stephen Crabb described the news as a "wake-up call".
The former Secretary of State for Wales said: "The enormous Airbus factory in North Wales is one of the jewels in the crown of UK manufacturing.
This is a wake-up call. A pragmatic, sensible Brexit that protects trade & jobs is vital."