President Rodrigo Duterte is ready to argue his case personally before the International Criminal Court, a Palace official said on Thursday.

Presidential Spokesperson Harry Roque also expressed belief that the complaint filed by Filipino lawyer Jude Sabio against Duterte in relation to his bloody war on illegal drugs would not prosper.

Roque issued the statement after the Philippine mission in The Hauge was informed by the Office of Prosecutor of the ICC that it is opening "preliminary investigation on the alleged acts associated to the campaign against illegal drugs covering the period of July 2016."

"We note that this is only a preliminary investigation. The Office of the Prosecutor is merely exercising his mandate to determine whether there is reasonable basis to proceed with an investigation into a situation pursuant to criteria in the Rome statute namely: jurisdiction, admissibility and interest of justice, lest the opposition got to claim for a victory," explained Roque, a lawyer.

He said he and Duterte discussed the ICC's action "extensively for more than two hours" on Wednesday night.

"The president has said that he also welcomes this preliminary examination because he is sick and tired of being accused of the commission of crimes against humanity. This is an opportunity for him to prove that this is not subject to the court’s jurisdiction because of both complementarity that domestic courts and the fact that we have a domestic international humanitarian law statute in our jurisdiction, are reasons enough for the Court not to exercise jurisdiction," Roque said.

But he added, "the president has said that if need be, he will argue his case personally before the International Criminal Court."

"He said he wants to be in Court and put the prosecutor on the stand," he said.

Roque said the president has the suspicion that the "domestic enemies of the state" were behind the petition against him.

Sabio, with the backing of opposition Senator Antonio Trillanes IV and Magdalo party-list Rep. Gary Alejano, filed the petition against Duterte last year.

Duterte allegedly violated the Articles of Rome Statute through commission of mass murder or extrajudicial executions constituting crimes against humanity.

When he assumed office, Duterte declared a war against illegal drugs. He has been criticized due to the deaths of thousands of drug suspects. Celerina Monte/DMS