Suffolk businesses have been told to expect "major disruption" as workers at the Port of Felixstowe look set to walk out next month.
Eighty per cent of the 1,800 Unite members at the port took part in a vote on industrial action, with a majority of 92% voting in favour.
The dispute follows the Felixstowe Dock and Railway Company offering a pay increase of 5% to its workers.
Union bosses say this is an effective pay cut with RPI currently standing at 11.9%.
Unite leaders and port chiefs met on Thursday for last-minute talks to avert strike action.
However, the union says no improved offer has been made, meaning strikes are likely.
Any action at Britain's largest container port could mean vessels have to be diverted away from Felixstowe to ports elsewhere in the UK or Europe.
CEO for New Anglia LEP, Chris Starkie said: "Felixstowe Port plays a critical role in keeping goods moving in our region, and this and other planned industrial action promises to cause major disruption to the supply chain, local businesses and consumers.
"I would urge businesses to start making contingency plans now."
Unite has paused announcing strike action to give Felixstowe port's owners a "short window of opportunity" to return to the negotiating table with a "realistic offer".
The union says that if the company fails to take advantage of this gesture then strikes are set to begin next month.
Sharon Graham, Unite general secretary, said: “This is a staggeringly wealthy company that can fully afford to make its workers a fair pay offer but it is choosing not to. Managers are cynically prioritising paying dividends over workers' wages.
“Unite is committed to enhancing the jobs, pay and conditions of its members and it will be giving the workers at Felixstowe its complete support until this dispute is fully resolved and a fair pay offer is made.”
Miles Hubbard, Unite regional officer, added: “Strike action at Felixstowe will inevitably cause huge disruption across the UK’s supply chain but this is a dispute of the company’s own making due to its failure to make its workforce a realistic pay offer.
“As an act of goodwill, Unite is providing the company with a short window of opportunity to make a vastly improved offer. If the Felixstowe Dock and Railway Company fail to grasp this opportunity, then strikes will be announced and the resulting disruption will occur.”
The Port of Felixstowe says it believes its offer to be satisfactory and is making further arrangements to avoid strikes.
A spokesman for the port said: “The company made what we believe to be a very fair offer and we are disappointed with the result of the ballot.
"The union has agreed to our request to meet with ACAS next week and we hope that any industrial action can be avoided.”
A spokesman for The Department for Transport said: “We are aware of ongoing pay discussions and a ballot for industrial action at the Port of Felixstowe. We strongly encourage both parties to remain at the table and avoid industrial action.
“We remain in close contact with the port on the potential impacts on port operations if any action takes place in future.”
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here