The Queensland Premier Annastacia Palaszczuk has announced further financial support for a $1.8 billion project to extend the national electricity grid into the outback north-west of the state.

Palaszczuk said her Government had signed an agreement with proponents of the CopperString 2.0 project to proceed to the next level, declining to reveal the exact size of the new investment.

CopperString 2.0 involves the construction of a 1,100 kilometre high-voltage transmission line from Townsville to Mount Isa and is expected to create 400 construction jobs.