The WSJ says that Tesla has been in talks with officials in Nevada about the expansion, which would see the Gigafactory almost double in size.

Tesla has been tight-lipped about its plans for the Semi, which is due to be unveiled later this year. But the WSJ says that the company plans to make the trucks at the Gigafactory, and that it has already started training workers to do so.

The Gigafactory is already producing batteries for Tesla's cars, and the expansion would see it become the main production site for the company's Powerwall home batteries.

The WSJ says that the expansion would create "thousands of jobs" in Nevada, and that Tesla is also considering building a second factory in the state.