Philippine President Rodrigo Duterte said on Wednesday he was ready to discuss any issues with Barack Obama when they meet in Laos next week, but added that the U.S. president must listen to him first before bringing up the question of human rights.

Washington has expressed concern about a surge in drug-related killings since Duterte became president two months ago promising to wipe out narcotics in the Southeast Asian nation.

Asked if he would be willing to discuss human rights at his meeting with Obama on the sidelines of an East Asia summit on Sept. 6, Duterte told reporters: "Depends to what degree".

"They must understand the problem first before we talk about human rights. I would insist, listen to me: this is what the problem is, then we can talk."

Police data released on Tuesday showed that the number of drug-related killings since Duterte took office now stands at around 2,000, nearly half of them in police operations and the rest in shootings by unidentified gunmen.

Duterte, who is nicknamed "the Punisher", has been unapologetic over unleashing the police on drug users and dealers and has responded robustly to criticism from the United Nations and other countries over his campaign.

Recently he lashed out at Washington's ambassador to the Philippines, branding him a "gay son of a whore".

The White House said on Monday that Obama would raise concerns about some of Duterte's "recent statements" when the two men meet next week.

However, it said there were also important security issues for the two closely allied countries to discuss, particularly tensions over navigation in the South China Sea. China has been incensed by a ruling against its claims in the South China Sea by an international court, a case initiated by Manila.

Duterte said he would also hold talks with China, which will be represented at the Laos meeting by Premier Li Keqiang. Media reports said he would also meet Russian President Vladimir Putin.