In addition to the fire risk, the site is particularly ill-suited for landfill due to the proximity of a high-voltage power line, and the fact that the area contains one of the biggest sources of fresh water in the country, the Commission said Thursday.

Slovenia had agreed to address the problem and clean up the waste tyres, but "the very slow rate of progress has led the Commission to call Slovenia before the Court of Justice," the Commission said.

The Commission opened infringement proceedings in October 2012, with a reasoned opinion following in March 2013. Slovenia presented a timetable for clean-up but has failed to respect it.

The site is located in Lovrenc na Dravskem polju, where more than 40,000 tonnes of highly flammable waste tyres have been stored since 2006.