(Corrects RIC for Bank of China from to)
BEIJING, April 29 (Reuters) - Bank of China said on Wednesday it had hired lawyers to formally send a letter to CME Group, urging the U.S. exchange operator to investigate reasons behind "abnormal fluctuations" in crude oil futures prices on April 21.
Retail investors who shoulder the loss may have lost more than 9 billion yuan ($1.3 billion) from BoC's crude oil product, financial news outlet Caixin reported on Sunday citing unnamed sources, after the CME's May WTI crude contract sank to -$40 a barrel.
The bank said it would continue negotiating with investors, shoulder responsibilities under the current legal framework and was seeking to respond to customers' "reasonable requests" as early as possible.
Reporting by Leng Cheng and Brenda Goh, writing by Tom Daly and Yilei Sun Editing by Chizu Nomiyama