Mumbai, Nov 16 : UCO Bank has lodged a complaint with the Central Bureau of Investigation (CBI) after a technical glitch in its Immediate Payment Service (IMPS) led to the erroneous transfer of Rs 820 crore into various customers' accounts but the bank did not receive the money. "We further inform that by taking various proactive steps, Bank blocked the recipients' accounts and has been able to retain and recover around Rs 649 crore out of Rs 820 crore which is about 79 per cent of the amount," UCO Bank said in a BSE filing on Thursday. The incidents occurred between November 10 and November 13, and the facility was stopped on Wednesday, it said in the stock exchange filing. "The bank, as a precautionary measure, has made the IMPS channel offline and is working closely with stakeholders to resolve the issue and restore the IMPS services at the earliest. The matter has been reported to law enforcement agencies for further action,' UCO Bank said. UCO Bank claimed that this is an "internal technical issue as a result of which bank customers received some erroneous credits via IMPS". Some bankers are of the view that it could be a cyber attack on the UCO Bank system. IMPS is another real-time payment service, but the distinguishing factor is that IMPS is available 24x7 and you can avail the service even on bank holidays. Using IMPS, you can transfer comparatively lower amounts, up to Rs 2 lakh, instantly. /IANS