Philippine President Rodrigo Duterte warned President Barack Obama on Monday not to question him about extrajudicial killings, or "son of a bitch I will swear at you" when they meet in Laos during a regional summit.

Duterte said before flying to Laos that he is a leader of a sovereign country and is answerable only to the Filipino people. He was answering a reporter's question about how he intends to explain the extrajudicial killings to Obama. More than 2,000 suspected drug pushers and users have been killed since Duterte launched a war on drugs after taking office on June 30.

In his typical foul-mouthed style, Duterte responded: "I am a president of a sovereign state and we have long ceased to be a colony. I do not have any master except the Filipino people, nobody but nobody. You must be respectful. Do not just throw questions. Putang ina I will swear at you in that forum," he said, using the Tagalog phrase for son of a bitch.

Duterte has earlier cursed the pope and UN Secretary-General Ban Ki-moon.

It isn't clear whether Obama plans to raise the issue of extrajudicial killings with Duterte during a meeting on the sidelines of the summit of the Association of Southeast Asian Nations.

Speaking at a G20 meeting in China, Obama responded to Duterte's statement. "Clearly he's a colorful guy," the president said. "Obviously the Filipino people are some of our closest friends and allies and the Philippines is a treaty ally of ours. But I always want to make sure that if I'm having a meeting that it's actually productive and we're getting something done," he told reporters in the eastern Chinese city of Hangzhou.

"Who is he to confront me?" Duterte said, adding that the Philippines had not received an apology for misdeeds committed during the U.S. colonization of the Philippines.

He pointed to the killing of Muslim Moros more than a century ago during a U.S. pacification campaign in the southern Philippines, blaming the wounds of the past as "the reason why (the south) continues to boil" with separatist insurgencies.

Duterte also pointed to human rights problems in the United States.

Last week, Duterte said he was ready to defend his bloody crackdown on illegal drugs, which has sparked concern from the U.S. and other countries.

Duterte said he would demand that Obama allow him to first explain the context of his crackdown before engaging the U.S. president in a discussion of the deaths.

The White House had no immediate reaction to Duterte's comments. Obama has been attending a meeting of the Group of 20 nations in Hangzhou, China.