Jaguar Land Rover-owner Tata is set to announce plans to build a flagship electric car battery in Somerset.
People familiar with the matter said the investment would be officially announced on Wednesday.
The government is providing subsidies worth hundreds of millions of pounds, sources said.
Some in the car industry have described the plant as the most significant investment in UK automotive since Nissan came to Britain in the 1980s.
The government has been criticised for lacking a clear industrial strategy and falling behind the US and EU in attracting investment.
Some industry insiders hope that the Tata battery investment will open the door to further battery investments in the UK, which currently only has one plant in operation next to Nissan’s Sunderland factory, and one barely on the drawing board in Northumberland.
By contrast the EU has 35 plants open, under construction or planned.
The investment could lead to the creation of up to 9,000 jobs in the Bridgwater area.