The industrial action would mean the port would be "grinding to a halt", the union said, though it didn't provide details on the start or duration of the strike.

The workers at Mersey Docks and Harbour Company (MDHC), which is part of Peel Ports, the second largest port group in the country, voted 99% in favour of the strike.

"Our members at MDHC have Unite’s complete backing and support in these strikes for a fair pay rise,” Unite general secretary Sharon Graham said.

Rising prices and stagnant real wage growth has seen a wave of strikes across Britain with rail, legal, aviation and refuse workers voting to take industrial action.

Peel Ports said it had offered a 7% increase to basic pay on top of a 4.5% pay increase last year and other improvements to shifts, sick pay and pensions.

The Bank of England forecasts inflation in the UK will reach 13% this year and Unite said this would result in a real terms pay cut for workers.

Peel Ports urged the union to keep talking to resolve the dispute.