The European commission has warned the UK that it has not properly transposed an EU Directive on the storage of waste metallic mercury.
The reasoned opinion, sent out at the end of September, states that the commission is not convinced that amendments to the environmental permitting regulations in England and Wales, and to Scotland's landfill regulations, have set out sufficient action on the issue.
The UK has two months to respond, or risk the case being referred to the EU court of justice. Mercury is highly toxic to humans, ecosystems and wildlife. A Defra spokesperson said: "We take this matter seriously and are confident that our legislation meets the Directive's requirements."