President Rodrigo Duterte has shrugged off the move of some American senators to ban Philippine officials involved in the detention of opposition Senator Leila de Lima in the US.

In an interview before his departure for Russia Tuesday night at the Ninoy Aquino International Airport Terminal 2, Duterte said he would only act once the proposal is adopted by the US legislators either through the State Department or by talking to his counterpart, President Donald Trump.

"So if they decide to report it out of the committee to the plenary for adoption and it becomes - it is now ripe, it becomes a matter now between two states, then that is the time maybe the State Department or Trump and I will have to talk. And I will talk," he said.

But Duterte said currently it is not ripe to react on the proposal by some US lawmakers.

"When it becomes ripe, then I will say my piece...these are voices of members of a committee. And if that committee will report the resolution to the plenary and the plenary would adopt or join them, and then that would be the act of Congress," he said.

Duterte said he does not deal individually with the congressmen or senators in the US.

"It's not act of state. It does not carry the mandate of the entire Senate. So if there is one or two or three who says these things exist in the Philippines, let them," he added.

US Senators Patrick Leahy and Dick Durbin were among those seeking to deny entry of Philippine government officials who were involved in the detention of De Lima, who is facing charges due to her alleged involvement in the illegal drug trade in the national penitentiary when she was still the secretary of Justice.

De Lima denied the charges, saying she is a victim of political persecution. Celerina Monte/DMS