Jan 24 (Reuters) - Australian diversified miner South32 Ltd on Monday posted a near 15% drop in its second-quarter metallurgical coal output, hurt by an extension of a longwall form of mining at its flagship Illawarra project in New South Wales.

Production of metallurgical coal, used to make steel, fell to 1.2 million tonnes (Mt) in the three months to Dec. 31 from 1.4 Mt a year earlier.

The diversified miner also warned of potential impact in the second half from workforce restrictions due to the coronavirus pandemic in New South Wales. (Reporting by Sameer Manekar and Riya Sharma in Bengaluru; Editing by Chris Reese)