President Barack Obama canceled what would have been his first meeting with Filipino President Rodrigo Duterte, after Duterte described Obama in vulgar terms, a White House spokesman said on Tuesday.

Duterte, a plain-spoken populist known for his colorful remarks and his campaign against illegal drugs in which thousands of people have died, described Obama as a "son of a b****" to reporters on Monday, a day ahead of the planned meeting in Laos, where South Asian leaders are meeting for annual summits.

Obama learned about the insult as he emerged from the Group of 20 summit in Hangzhou, China. At a news conference, he said he had told his aides to speak with Philippine officials "to find out is this, in fact, a time where we can have some constructive, productive conversations," leaving little doubt that the meeting would proceed as planned.

"I always want to make sure that if I'm having a meeting, that it's actually productive and we're getting something done," Obama told reporters.

Instead, Obama now plans to meet later on Tuesday with South Korean President Park Geun-hye, said Ned Price, spokesman for the White House National Security Council - a meeting where the response to North Korea's latest missile tests is expected to be on the agenda.

Obama arrived in Vientiane just before midnight on Monday, for the first visit by a sitting U.S. president to Laos, where he wants to begin to address the legacy of U.S. bombing during the Vietnam War.

He was set to give an address on the importance he has placed on Southeast Asia in his foreign and economic policy during his two terms in office, which will end on Jan. 20, setting the stage for three days of meetings with regional leaders.

The White House had said Obama did not plan to pull any punches on his concerns about human rights abuses in the Philippines, its treaty ally, when meeting Duterte.

Duterte won the presidency in May as he promised to suppress crime and wipe out drugs and drug dealers, and a wave of extrajudicial killings has followed.