Thieves have stolen 114 tonnes of cobalt from a secure warehouse in Rotterdam’s port area, local broadcaster RTV Rijnmond reported on Friday.

The haul has a value of some €7m and must have been removed by lorry but it is unclear as yet how the thieves were able to do this, RTV Rijnmond said. Cobalt is a rare mineral used largely for the production of batteries and pigments.

The theft from the Vollers warehouse took place between July 5 and July 9, the Minor Metals Trade Association said in a statement issued to members earlier this week.

‘Additional monitoring and security have been implemented since the discovery of the theft, and Vollers are working closely with police and insurers,’ the MMTA said.