WASHINGTON (REUTERS) - US President Donald Trump has developed a friendly relationship with Philippine President Rodrigo Duterte, a senior administration official said on Tuesday (Oct 31), despite Duterte's often profanity-laden tirades against the United States.

"I think there's a warm rapport there and he's very much looking forward to his first in-person meeting with President Duterte," the US official told reporters during a background briefing on Trump's Nov 3-14 trip to Asia.

The two leaders have become friendly during telephone conversations and exchanges of letters, the official said.

Trump will travel to Asia amid rising tensions over North Korea's nuclear and missile programmes. He will be in Manila on the last leg of his trip, which includes visits to Japan, South Korea, China, and Vietnam, to attend the Asean leaders' summit.

Duterte has attacked the United States verbally, chiding Washington for treating the Philippines "like a dog," despite the two nations' longstanding relationship.

The Philippines' leader announced his "separation" from the United States during a visit to Beijing a year ago, declaring he had realigned with China as the two agreed to resolve a South China Sea dispute through talks.

Duterte is accused by international human rights groups of supporting a campaign of extrajudicial killings of drug suspects in the Philippines, which his government denies.

The Philippine leader was infuriated by expressions of concern by members of former President Barack Obama's administration about extrajudicial killings in the Philippines.

But Trump, in a phone call to Duterte in May, praised the Philippine leader for doing an "unbelievable job on the drug problem" despite human rights groups' condemnation of Duterte's drug crackdown, in which thousands of people have been killed.