Philippine foreign affairs spokesman Charles Jose confirmed on Wednesday that Manila's envoy in Washington had been summoned, saying he had been "invited to the State Department to discuss the entire breadth of Philippines-US relations."

"Philippine-US relations remain strong," he told the news agency AFP on Wednesday.

However, the US State Department said that the Filipino charge d'affaires, Patrick Chuasoto, had been summoned to discuss the president's comments.

"We had that conversation," department spokeswoman Elizabeth Trudeau said. "I think what we were seeking is perhaps a better understanding of why that statement was made," she added.

The Philippines, which was once a US colony, has long shared a military treaty with its former colonial power. But tensions in the region, in part connected with China's strategic military ambitions, have exacerbated concerns in Washington that Manila could shift its foreign policy alignment under Duterte, who took office in May, .

Not very diplomatic language

Duterte, in televised comments made Friday in the Tagalog language, used a homophobic slur when criticizing US Ambassador Philip Goldberg. "As you know, I'm fighting with (US Secretary of State John Kerry's) ambassador. His gay ambassador, the son of a whore. He pissed me off," Duterte said.

"He [Goldberg] meddled during the elections, giving statements here and there. He was not supposed to do that," Duterte said on Friday.

Duterte came to power in a landslide in May after a series of comments attacking a range of people, including the pope. He also suggested he wanted to rape a "beautiful" Australian missionary who was sexually assaulted and murdered in a 1989 prison riot in Davao, comments that were strongly criticized during Duterte's election campaign by Goldberg and the Australian ambassador.

jbh (dpa, AFP)