Bank of the Philippine Islands said Friday there was no breach in its client confidentiality protocols after deposit account details of Davao City Mayor Rodrigo Duterte, who is leading in opinion polls, were made public.

The Ayala-led lender said its data protection practices were among the strictest in the industry and it was committed to preserving clients' trust.

"Our internal investigation reveals that there has been no such breach," BPI said in a statement.

Outraged Duterte supporters have bombarded the bank's Facebook page with threats to close their accounts and transfer to rival banks saying the mayor's privacy was violated.

Sen. Antonio Trillanes IV, who is supporting Duterte's closest rival, Sen. Grace Poe, claimed earlier this week that Duterte was keeping P211 million in BPI's Julia Vargas branch.

READ: Duterte to bare BPI account on Monday: lawyer

Duterte's lawyer, Peter Lavina, initially denied that the account existed, but the tough-talking mayor eventually owned up to it and said it contained much less money.

TIMELINE: Duterte camp denies, admits BPI account

The revelation came as Duterte padded his lead over Poe in the last two rounds of surveys despite controversial remarks he made over the rape of an Australian missionary in Davao in 1989.