CORRECTED-UPDATE 1-China watchdog raps ICBC after brokerage accounts glitch

(Corrects day in second par from Monday to Tuesday and in third par from Tuesday to Wednesday) SHANGHAI, Apr 1 (Reuters) - China's securities regulator has ordered the country's largest listed bank, Industrial and Commercial Bank of China Ltd (ICBC) , to improve operations after a glitch earlier this year left investors unable to complete around 5 billion yuan ($807 million) of transactions. The China Securities Regulatory Commission (CSRC) said late on Tuesday that the bank must fix its systems after they failed to register some transfers of funds from brokerage accounts to investors' bank accounts in January. That contravened rules, the commission said, in a statement posted on its official website. Calls to ICBC seeking comment on the regulator's move went unanswered on Wednesday morning. The glitch affected 54,709 customers at 90 brokerages. Chinese investors who trade in shares via the country's brokerages keep their trading funds in bank accounts, which are then linked to the brokers. The CSRC asked the bank to provide a report on the matter by May 10, after which the watchdog will organise an inspection. (1 US dollar = 6.1400 Chinese yuan) (Reporting by David Lin and Engen Tham; Editing by Kenneth Maxwell)