A major container shipping company has announced it will no longer use the Port of Felixstowe from next year.
Maersk said its operations at the Suffolk port would cease from February following a review of its network.
The firm said it had concluded that the London Gateway on the Thames estuary in Essex was "the most optimal port to serve our customers" in the UK.
It said it expected to share further details "over the next couple of weeks".
In a statement on its website, Maersk said: "This change will affect the Asia-Europe trades under the scope of the Gemini co-operation.
"The previously announced Middle East-Europe (London Gateway) and Trans-Atlantic (Southampton) Gemini services remain unchanged.
"The rest of our own operated services outside the scope of the Gemini Co-operation also remain unchanged."
The company added it remained "committed" to its customers during the "transition to this new network".
The news comes a month after it was announced £2bn is to be pumped into expanding London Gateway and London Stansted Airport.
Jenny Riddell-Carpenter, Labour MP for Suffolk Coastal, said: "We need to be cautious in our reaction [to this news].
"It's clear that it's disappointing for us, the Port of Felixstowe and the wider community that they [Maersk] have made that decision.
"We haven't heard anything from the Port of Felixstowe about this. It is one of the busiest ports in the UK; it has a huge offering both nationally and globally.
"I'll be doing everything I can to make sure it continues to be a global player."
In a statement, the Suffolk Chamber of Commerce said: "Whatever the full commercial rationale for Maersk’s relocation to Thames Gateway, it makes it even more important that the rail and road infrastructure in and out of the Port of Felixstowe is the very best it can be to retain and attract businesses, as competition from other ports looks set only to intensify."