BEIJING, April 23 (Reuters) - China's Tianqi Lithium said on Tuesday it is expecting a significant net loss of 3.6-4.3 billion yuan in the first quarter, citing a sharp drop in the sales price of lithium products due to market fluctuations.

Tianqi posted a net profit of 4.9 billion yuan ($676.38 million) in the same period last year, it said in a Shenzhen Stock Exchange filing.

The forecast prompted the Shenzhen bourse to send a query to the lithium giant to specify the reasons for the significant increase in losses, and explain whether there is a risk of sustained losses. ($1 = 7.2445 Chinese yuan renminbi) (Reporting by Ethan Wang, Ella Cao and Ryan Woo; Editing by Alison Williams)