Marijuana growers are stealing almost €200m worth of electricity a year, national grid group Netbeheer Nederland said on Thursday.

They estimate that some 30,000 plantations are currently using stolen electricity, accounting for almost one billion kilowatts a year. That is more than the total domestic usage in Rotterdam, the organisation said.

The €200m is made up of €60m in electricity charges and €135m in lost tax income.

Last year, officials cut the power supply to almost 2,600 plantations. The illegal networks, they say, pose a serious fire risk.