(Updates with data on lithium exports) May 7 (Reuters) - Chile posted an April trade surplus of $612 million, the country's central bank said on Tuesday, even as the value of the Andean country's coveted copper and lithium exports slid sharply from the previous period.

Total copper exports hit $2.78 billion in April, down 4.1 percent from the same month in 2018, while lithium carbonate exports dropped to $49 million in April, their lowest value since December 2017, according to bank statistics.

The drop in export values follows a difficult first quarter for Chile's lithium and copper miners.

State miner Codelco and others were forced to suspend or scale back operations in January following unusually heavy rains in the country's northern desert, with operational issues and falling ore grades continuing to weigh on output at Chile's top deposits.

Chile exported lithium carbonate at an average price of $12,183 per ton in the first quarter, down nearly 1 percent from the previous period, according to a report from Bloomberg.

Chile is the world´s top producer of copper and second largest producer of lithium.

All figures in billions of dollars unless otherwise noted: April 2019 March 2019 April 2018 Trade balance $612 mln $607 mln $770 mln Exports $5.866 $6.194 $6.262 Imports $5.254 $5.587 $5.492 Copper export revenue $2.782 $2.970 $2.902 (Reporting by Dave Sherwood; editing by Dan Grebler and G Crosse)