President Barack Obama has called off a meeting with controversial Philippine President Rodrigo Duterte, who had insulted him earlier.

Rodrigo Duterte was responding to Barack Obama’s promise to raise the issue of drug-related extra-judicial killings in the Philippines at their meeting.

The Filipino leader is known for his colorful language, though this time it has had a diplomatic impact, correspondents say.

Rodrigo Duterte has now said he regrets the remark.

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

Rodrigo Duterte and Barack Obama are among leaders gathering for the Association of Southeast Asian Nations (ASEAN) summit in Laos.

Barack Obama, who flew to Laos after attending the G20 meeting in Hangzhou, China, had been set to raise concerns about human rights abuses in the Philippines.

Speaking in Manila on September 5 before he left for Laos, Rodrigo Duterte bristled at the suggestion, saying it was “rude” and cursing the US president: “Putang ina (son of a whore) I will swear at you in that forum.”

Rodrigo Duterte added: “We will be wallowing in the mud like pigs if you do that to me.”

The Filipino leader then referred to the anti-drugs campaign that has led to the killing of 2,400 suspected drug dealers and users in the Philippines since he took office in June: “The campaign against drugs will continue. Many will die, plenty will be killed until the last pusher is out of the streets….until the [last] drug manufacturer is killed we will continue.”

Barack Obama initially appeared to play down the insult saying that he had asked his aides to work out if this is “a time where we can have some constructive, productive conversations”.

His aides later canceled the talks.

Barack Obama’s last scheduled trip to Asia as president has not been without incident: he was also caught up in a protocol row with hosts China over his arrival in Hangzhou.

This is not the first time President Rodrigo Duterte has used such a language against prominent figures.

He has also insulted Pope Francis, the US ambassador to Philippines and Secretary of State John Kerry.

Correspondents say that such colorful talk plays well with the domestic audience, but it could cost Rodrigo Duterte on the international stage.

The UN has repeatedly condemned Rodrigo Duterte’s policies as a violation of human rights.

In August, two UN human rights experts said Rodrigo Duterte’s directive for police and the public to kill suspected drug traffickers amounted to “incitement to violence and killing, a crime under international law”.

This round of ASEAN talks comes against the backdrop of tensions over China’s territorial ambitions in the South China Sea – the Philippines and the US are key players in that debate.