Russia said on Thursday (June 11) it had charged the mayor of the remote Arctic city of Norilsk with criminal negligence over what investigators said was his bungled response to last month's fuel spill.
Around 21,000 tonnes of diesel leaked into rivers and subsoil on May 29 from a power station in Norilsk.
Greenpeace has compared the incident to the 1989 Exxon Valdez oil spill off Alaska.
Russia's Investigative Committee handles probes into major crimes and said mayor Rinat Akhmetchin failed to coordinate and organize emergency measures, to contain and control fallout from the spill.
Committee spokeswoman Svetlana Petrenko.
"The Russian Investigative Committee continues establishing all the facts regarding diesel fuel spill from the tank in Norilsk as well as environmental disaster that followed. The investigators have started a criminal case regarding criminal negligence of the head of Norilsk city Rinat Akhmetchin and failure to perform his duties in case of an emergency."
If found guilty, he could face up to six months in jail.
The charges come just a day after investigators arrested three managers from the power station.
They are suspected of having continued to use an unsafe fuel storage tank that had needed repairs since 2018.
President Vladimir Putin last week berated Norilsk Nickel over the leak and scolded the region's governor after he said authorities had only learned of the disaster from social media two days after it happened.