MANILA (UPDATE) - The government's top lawyer on Tuesday said the Senate should no longer pursue its investigation into the alleged hidden wealth of President Rodrigo Duterte as it would only be a "waste of time."

Solicitor General Jose Calida said the inquiry into the President's wealth had been terminated by the Office of the Ombudsman so there would be no need for a Senate inquiry.

"The Senate should stop this investigation, they're wasting their time because [Sen. Antonio] Trillanes' evidence, as I said, is garbage," he said in a press conference.

"It will not stand the scrutiny of senators," he added.

OSG shows Ombudsman letter saying investigation on Trillanes complaint vs President Duterte was already closed and terminated pic.twitter.com/K4ht5fkbk4

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Senator Antonio Trillanes IV on Tuesday said he would resign as a senator if his allegations are proven false.

"If what I have is nothing but garbage, then why are they panicking? And why can't Mr. Duterte just accept my challenge for him to sign a waiver and if I am wrong in my allegations then I would resign immediately as senator and voluntarily walk-in any jail of his choice," he said.

The Ombudsman's earlier investigation into Duterte's wealth is connected with Trillanes' allegations that the chief executive kept hidden wealth.

Trillanes, a staunch critic of the President, was the one who proposed the Senate investigation into the Dutertes' alleged undeclared wealth.

• Ombudsman investigates Duterte family's wealth

Trillanes said the inquiry would look into bank documents under the name of the Dutertes, which allegedly showed undisclosed transactions exceeding P500,000.

The transactions, he said, "may have violated the Anti-Money Laundering Act."

• Trillanes wants Senate probe on Duterte, Sara's alleged bank accounts

Malacañang earlier said that the President "has nothing to hide."

At the briefing on Tuesday, Calida said he was only informed of the termination of the Ombudsman's investigation after he wrote a letter to Overall Deputy Ombudsman Arthur Carandang, who informed him that the investigation "has been closed and terminated."

The Solicitor General then questioned why Ombudsman Conchita Carpio Morales did not inform the public that her office's investigation into allegations against the President had ended.

A letter presented by Calida from the Office of the Ombudsman showed that the investigation into the President's alleged undeclared wealth ended on Nov. 29, 2017.

"She has the constitutional duty to publicize matters covered by investigation when circumstances so warrant it and with due prudence. This case involves the President of the Philippines. Why did she withhold this information?" he said.

Senate President Aquilino "Koko" Pimentel III, an ally of the President, previously said the Senate was not the proper body to investigate the matter.

• Pimentel says no to Senate probe on Duterte bank accounts

The Ombudsman's investigation had pitted the executive against the constitutional body, with the Palace filing grave misconduct charges against Carandang for the supposed illegal disclosure of the President's and his family’s bank transactions.

• Palace files admin raps vs deputy ombudsman
• Ombudsman defies Palace, won't enforce Carandang suspension

-with a report from Sherrie Ann Torres, ABS-CBN News