The European Commission says Greece must take steps to prevent the pollution of Lake Koroneia or face potential legal action.

Greece's Kathimerini newspaper said Friday the European Union branch informed the Greek government in a letter that EC inspectors were not pleased with the level of pollution they found at the European Union-protected wetland in northern Greece.

The commission's letter detailed the use of the lake as a dumping site for local industries' toxic materials as well as the presence of illegal water bores at the site.

Kathimerini said, citing unidentified local sources, the Greek Agricultural Development Ministry has failed to use funds earmarked for shutting down such water bores.

EC officials also used the letter to remind Greek officials they are required to protect the lake as per EU legislation.

Greece's Ecologist Greens party said in a statement the EC letter of warning was prompted by the slow efforts of local authorities.

"The progress in implementing protective measures has proven to be extremely slow ... and as a result the commission has sent this warning to Greece," the ecologist group said.