MADURAI, India - A minor leak has been detected in the sulphuric acid storage plant in Vedanta's south Indian copper smelter, a government official said on Sunday, about a month after the state ordered its shutdown after protests in which 13 people died.

Police opened fire on a crowd of protesters on May 22 calling for the shutdown on the grounds of pollution. The Tamil Nadu state government then ordered a permanent shutdown.

"A leakage was observed in the sulphuric acid storage plant. It doesn't look problematic, but we have decided to evacuate the storage tomorrow as a safety precaution," Sandeep Nanduri, the district's top administrative official, said on Sunday.

Vedanta Ltd, the Indian subsidiary of Vedanta Resources PLC which operates the smelter, did not immediately respond to a request seeking comment.

The smelter accounted for over a third of India's refined copper output, and India is set to see a rise in copper imports following the shutdown.

Sulphuric acid, a corrosive byproduct of smelting, is used by fertilizer and chemical companies as a raw material.

(Reporting by Sudarshan Varadhan; editing by Andrew Roche) ((Sudarshan.Varadhan@thomsonreuters.com; +911149548059; Twitter: https://twitter.com/turvytopsy @turvytopsy; Reuters Messaging: sudarshan.varadhan.thomsonreuters.com@reuters.net))