MANILA (BLOOMBERG) - Bank of the Philippine Islands (BPI) blamed an internal data-processing error for inaccurate balances in some of its customer accounts amid a flurry of claims on social media over unauthorised withdrawals and missing funds.

Some deposit accounts do not reflect accurate balances because the processing error had caused past transactions to be either debited or credited twice, the third-largest Philippine lender by assets said in an advisory on Wednesday (June 7). BPI shares lost 0.9 per cent as of 9.33am in Manila after opening 1.9 per cent lower.

"We are currently correcting the mispostings," BPI said. "We apologise for the inconvenience that this may have caused."

The bank pinned that advisory to the top of its Twitter feed, which was inundated with posts from users seeking answers or complaining that their account balances or banking services had been affected.

One user, identified on her account as Mary Jane Nario, 22, said earlier: "As of the moment, most of my workmates and I had a negative balance on our BPI payroll account. Is this a system problem?"

Some posts speculated that the bank had been targeted by hackers, a rumour denied by BPI president Cezar Consing in an interview with ABS-CBN News Channel. BPI took its system down this morning to correct the error, which happened last night, Mr Consing said, adding that no customer will lose money from the glitch.

The incident will be probed, central bank Deputy Governor Nestor Espenilla said in a mobile-phone text message, adding that Bangko Sentral Ng Pilipinas investigates "every single incident". BPI should be allowed to resolve the problem, Mr Espenilla, who becomes the central bank governor on July 3, told ABS-CBN separately.

BPI had 7.9 million clients and 1.4 trillion pesos (S$39 billion) of deposits at the end of 2016, according to its annual report. The bank's shareholders include Manila-based Ayala Corp, the Roman Catholic Archbishop of Manila and Singapore's GIC.