Sirius Minerals has been forced to cancel plans to issue a $500m (£403m) bond for a fertiliser mine it is developing in the North York Moors.
It paused the bond issue last month, but has now said it cannot issue it, blaming “market conditions”, including Brexit and lack of government support.
It will now undergo a six-month review of four different options for a new financing plan to resume the project.
The company’s shares fell by 63% in early trading on Tuesday morning.
The mine is due to open in 2021 and create more than 1,000 jobs.
Managing director Chris Fraser said: “This is the most prudent decision to give the company the time necessary to restructure its plans to move the project forward.”
In a statement, the company said it had asked the government for support but its request had been turned down.