MANILA, Philippines (AP) — An opposition senator pressed Philippine President Rodrigo Duterte on Thursday to publicly release details of his bank accounts to disprove allegations that he had large sums of undeclared money.

Sen. Antonio Trillanes IV first alleged Duterte had unexplained wealth during the presidential campaign last year. He told a news conference he was raising the issue again because Duterte has not yet revealed details of the more than 2 billion pesos ($40 million) he allegedly kept in bank accounts as a former city mayor.

Trillanes, one of Duterte's harshest critics and a navy officer once detained for a failed coup plot against a former president, said he would resign if Duterte can disprove the allegations.

Duterte angrily reacted to the allegations, saying he would resign immediately if Trillanes can prove his claim of large amounts amassed illegally.

"This is actually an old and rehashed issue," Duterte said in a statement, adding that Filipinos still voted him into power even after Trillanes made his allegations during the campaign.

Presidential spokesman Ernesto Abella said Duterte would not release those bank details "in response to grandstanding," but suggested the president may do so as part of a legal process.

The president's daughter, Mayor Inday Sara Duterte of Davao city, reacted to the allegations by saying if Trillanes could show where her alleged unexplained wealth "is right now and how it became illegal, let's get it and I'll give it to all of you."

"I know he will not release and he will not accept my challenge because it will be proven that he is really a corrupt official," Trillanes said.

In May, Trillanes released documents he said were handed to him by a concerned citizen purportedly showing 2.4 billion pesos ($48 million) flowed into Duterte's various bank accounts from 2006 to 2015, representing alleged unexplained wealth the mayor failed to declare as required by law.

Trillanes and Duterte's lawyer then went to a branch of the Bank of the Philippines Islands, where Duterte and his daughter allegedly had an undeclared deposit of more than 200 million pesos ($4 million) in a joint account.

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Lawyer Salvador Panelo said that Duterte had authorized him to request the bank to open the account but that bank officials told him it would take seven days to study the request. Trillanes said the account has not been opened to scrutiny.

Duterte has projected himself as a politician who rose from poverty and still lives a modest life in a rundown house in Davao city, where he served as a longtime mayor. He has faced criticism for his brutal crackdown on illegal drugs that has left thousands of mostly poor suspected drug users dead.

Duterte said his daughter was a lawyer who earned from her profession and that his common-law wife has built a fortune from her longtime doughnut business and by supplying pork meat to five shopping malls in Davao city.

Duterte did not directly address Trillanes's demand for disclosure of transaction details from specific bank accounts.