President Barack Obama cancelled what would have been his first meeting with Filipino President Rodrigo Duterte, after Duterte described Obama in vulgar terms, a White House spokesperson said today.

Duterte, a plain-spoken populist known for his colourful remarks and his campaign against illegal drugs in which thousands of people have died, described Obama as a “son of a bitch” to reporters yesterday, a day ahead of the planned meeting in Laos, where South-East 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”.

“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 today with South Korean President Park Geun-hye, said Ned Price, spokesperson 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 yesterday, for the first visit by a sitting US president to Laos, where he wants to begin to address the legacy of US bombing during the Vietnam War.

He was set to give an address on the importance he has placed on South-East 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.

Duterte said it would be “rude” for Obama to raise the human rights issue, and told reporters such a conversation would prompt him to curse at Obama, using a Filipino phrase for “son of a bitch”.

“Plenty will be killed until the last pusher is out of the streets. Until the (last) drug manufacturer is killed we will continue,” he said.

It’s not the first time Duterte has cursed at a world leader. He called Pope Francis a “son of a whore” in May, and called US Ambassador Philip Goldberg a “gay son of a whore”.

Yesterday, Obama said he recognised the importance of fighting the drug trade, but insisted it must be done under the rule of law.

Asean summit

The unusually open tensions threaten to overshadow the Association of South-East Asian Nations (Asean) and East Asia Summits in Laos from today to Thursday.

The 10-member Asean will meet leaders of other regional powers: China, Japan, South Korea, Australia, India, Russia and the United States.

The Philippines has been a key US ally in its dispute with China over the South China Sea, in which Washington blames Beijing for militarising a vital global trade route and jeopardising freedom of movement at sea and in the air.

China rejects those accusations, and in turn blames the United States for ratcheting up tensions unnecessarily. China claims most of the South China Sea, through which more than US$5 trillion of trade moves annually. Brunei, Malaysia, the Philippines, Taiwan and Vietnam have rival claims.

An arbitration court in The Hague in July invalidated China’s vast territorial claims to the waterway after a case was brought by the Philippines, a ruling that Beijing refuses to recognise.

Duterte said last month he expected all Asean members to support the arbitration court’s ruling, but that the Philippines would not raise the issue in Laos.

In another development, dpa reports that Duterte has expressed “regret” over expletive-laden remarks that prompted Obama to cancel a bilateral meeting in Laos.

“While the immediate cause was my strong comments to certain press questions that elicited concern and distress, we also regret it came across as a personal attack on the US president,” he said in a statement issued in Vientiane.

- Agencies