The European Commission will step up legal action against Italy on Wednesday over its handling of a rubbish crises in Naples, sources within the EU executive said.

"Yes, we expect to take this action," one of the sources with knowledge of the decision told Reuters.

Refuse collection in Naples and the surrounding Campania region stopped around Christmas when almost every dump was declared full. As a result, over 100,000 tonnes of garbage has piled up in the streets, triggering sporadic violence.

The Commission launched legal action against Italy last spring for breaching EU waste legislation amid a previous breakdown of rubbish collection and disposal in Campania.

Wednesday's action will take the form of a "reasoned opinion" or final warning before Italy is taken to the European Court of Justice -- Europe's highest court -- which can fine a country or order laws to be changed to comply with EU rules.

In January, EU Environment Commissioner Stavros Dimas warned he would take further action against the Italian government if it failed to tackle the problem more quickly.

He said the troubles were 14 years in the making and organised crime, often said to be heavily involved in the rubbish crisis, should not be blamed when the problem appeared to be a lack of political will to adopt the necessary measures.