A major expansion of Southampton Docks would be supported by the government, Chancellor Philip Hammond has said.
Speaking on a visit to the port, he welcomed plans to double capacity by using reclaimed land on the New Forest side of Southampton Water.
A previous scheme for Dibden Bay was rejected by Labour ministers in 2004.
Associated British Ports (ABP) said it hoped to complete development by 2026, but conservationists said important wildlife sites would be destroyed.
The application was turned down 12 years ago after a year-long planning inquiry.
At the time, the Labour transport minister Tony McNulty said an important factor was the environmental impact on internationally-protected sites.
The RSPB had argued the project would destroy marsh and mudflats which provide winter homes for 50,000 birds.
A local residents' campaign group said any development would blight thousands of lives.
On a visit to Southampton on Thursday, Mr Hammond said any application would no longer be subject to a local planning inquiry, but would be considered a National Infrastructure Project, subject only to approval by the secretary of state.
He said: "Obviously we have a planning system and proper procedures have to be followed, but in strategic terms I would support the development of this port."
Mr Hammond added that it was a "vital enabler of Britain's exporters who will play an ever more important role as we leave the European Union".
ABP, which has not yet made a renewed application for Dibden Bay, said it was having to turn business away because of a lack of capacity.
Chief executive James Cooper said: "There are jobs at the docks and all the way back through the supply chain to the manufacturers as well; it's all important to the British economy."
By 2030, the port forecasts exports of 840,000 vehicles a year, up from 700,000, and 4.2 million containers, up from 2.7 million.