A company extracting lithium from underneath remote countryside in County Durham says there are huge reserves of the mineral stored below the ground.

Northern Lithium said tests on a farm in Weardale showed there were "commercially viable" amounts in the area.

Lithium is needed for making batteries for electric vehicles and demand is expected to surge.

The company and its partner firm, Evove, now plan to build a commercial scale direct lithium extraction plant by 2027.

A small scale plant has been operating to demonstrate the mineral could be extracted from brines to make battery-grade lithium carbonate.

Northern Lithium said the goal was to produce at least 10,000 tonnes per year for electric vehicle manufacturing and other sectors.

Managing director Nick Pople said: "Consistent concentrations of lithium were found and the long term potential yields to scale this up to commercial operations were greater than we expected."

Trials conducted on the site at Ludwell Farm in Eastgate involved taking raw brines from the ground which are then put through a filtration system to separate the lithium from impurities.

Northern Lithium has the rights to explore 60,000 acres of land and said the North East could play a big role in providing a domestic supply instead of relying on imports.

The search for lithium has been likened to a 21st century gold rush, with rival firm Weardale Lithium granted planning permission by Durham County Council in January for its own work nearby.

Bishop Auckland MP Sam Rushworth said: "It's a really exciting opportunity.

"In the North East we've got two big buyers of batteries in Hitachi and Nissan and the best place in the UK for extracting lithium from under our feet."