Italian police arrest five Eni staff in waste trafficking inquiry

(Adds Eni statement)

MILAN, March 31 (Reuters) - Five staff at a treatment plant operated by oil major Eni (LSE: 0N9S.L - news) were placed under house arrest on allegations of illegal waste trafficking, the Italian police said on Thursday.

The arrests, of managers and workers, are part of a two-year-long investigation by regional anti-mafia prosecutors into waste management at the plant in southern Italy, a police statement said.

The plant is located in the Val d'Agri oil concession area in the Basilicata region, in which Royal Dutch Shell (Xetra: A0ET6Q - news) has a stake.

The police said part of the plant had been seized and that the alleged illegal activity had allowed the Italian state-controlled oil major to make "an unjust profit".

Eni pledged full cooperation with magistrates, adding it had temporarily suspended the arrested workers and was concluding internal checks of its own.

Production at the field of around 75,000 barrels per day had been halted for the time being, Eni said.

"Eni confirms... respect of legal requirements and best international practices," it said.

(Reporting by Stephen Jewkes; editing by John Stonestreet and Susan Fenton)