The Senate investigation has shown President Rodrigo Duterte or his close aide Christopher "Bong" Go were not involved in any anomalous contract involving the P15.7 billion Philippine Navy frigate project, Malacanang said on Monday.

In a press briefing, Presidential Spokesperson Harry Roque said Senator Antonio Trillanes IV even failed to show any evidence that would prove anomalies in the selection of the combat management system (CMS) for the two frigates to be purchased by the government from South Korean firm Hyundai Heavy Industries.

"The challenge to Senator Trillanes was to present the evidence. He already asked questions, (but) he did not present any evidence," said Roque, referring to the Senate probe on Monday.

He said it was easy to throw allegations, but it was hard to prove them.

"Let us not use our office in government to disseminate things which are not true," Roque said.

Trillanes earlier said he did not think that Go was involved in the controversy. But he said Go could have taken order from his superior who is the president.

Go allegedly meddled in the procurement of the CMS for the two frigates.

"I think it’s very clear, although the hearings are still continuing, it’s very clear that there was no such intervention on the part of SAP (Special Assistant to the President) Go," said Roque, one of the many Cabinet officials who went to the Senate to show support to Go.

He said there was no instruction from Duterte for the Cabinet members to go to the Senate.

"There was none. We went their voluntarily," he said.

Other Cabinet officials who were not speakers in the hearing, but were at the Senate, were Executive Secretary Salvador Medialdea, Cabinet Secretary Leoncio Evasco, and Solicitor General Jose Calida, among others.

In the same briefing, Roque indicated that the insistence of former Navy flag officer-in-command Vice Admiral Ronald Joseph Mercado to choose Tacticos Thales of the Netherlands over Hanwha Thales of Korea to provide CMS for the frigates could have personally benefited him.

"I was hoping that I could bring the documents here proving that he has even gone on trips to the office of Tacticos. But I failed to get it because the people in the Navy were still testifying. But perhaps tomorrow, I will get the documentary evidence that his interest in Tacticos goes beyond the reputation of Tacticos, that he has actually made several trips to the corporate headquarters of Tacticos. And of course, we don’t know why he made these trips to the Tacticos’ office," he said.

Mercado was unceremoniously removed as Navy chief last December over the frigate deal. Celerina Monte/DMS