Separately, the Philippines Presidential Communications Office said Xi committed more than $9 billion in low-interest loans to the country, with about a third of the loan offer coming from private banks. About $15 million in loans will go toward drug rehabilitation programs.
In opening remarks to his talks with Xi, Duterte hailed a warming of relations with China.
"China has been a friend of the Philippines and the roots of our bonds are very deep and not easily severed," he said. "Even as we arrive in Beijing, close to winter, this is a springtime of our relationship."
Xi, who greeted Duterte with full military honors at the Great Hall of the People, the seat of the ceremonial legislature in the heart of Beijing, said the meeting had "milestone significance." In a reference to the South China Sea tensions, Xi said that "although we have weathered storms, the basis of our friendship and our desire for cooperation has not changed."
While not mentioning the South China Sea specifically, Xi said that the two sides could set aside "issues on which an agreement is hard to reach" in their discussions, according to the official Xinhua News Agency.
Bilateral talks had been suspended after China seized control of Scarborough Shoal, off the main Luzon island in the northern Philippines, and the Philippines launched the arbitration process under Duterte's predecessor. The Philippines has insisted the ruling form the basis for any negotiations, while Beijing has insisted on the opposite.
Duterte has walked a tightrope in trying to mend damaged relations with China while defending his country's claims in the South China Sea.
The Philippine leader known for his devil-may-care, profanity-laden speeches had said he would not raise the issue that has angered China unless his Chinese counterpart first brought it up, out of "courtesy" to his host.
Duterte's visit showed his desire for economic benefits, while the Chinese want to manage issues between the two countries through bilateral talks, Bonnie Glaser, senior adviser for Asia at the Center for Strategic and International Studies in Washington, D.C., wrote in an email.
"This is an interesting courtship between China and the Philippines," Glaser wrote. "It remains to be seen whether China will seek Manila's respect for Chinese sovereignty. That would likely be a deal breaker."
In Washington, officials seemed puzzled by Duterte's comments.
"We are going to be seeking an explanation of exactly what the president meant when he talked about separation from us," Kirby told reporters. "It's not clear to us exactly what that means and all its ramifications."
Kirby said the top U.S. diplomat for Asia, Daniel Russel, is traveling to Manila this weekend and would hold conversations with Filipino government officials.
"It isn't just the United States that is baffled by this rhetoric," Kirby said. "We have heard from many of our friends and partners in the region who are likewise confused about where this is going."
Despite Duterte's increasingly sharp criticism of the United States, Kirby said the two countries' 70-year alliance hasn't yet been affected.
"We remain rock solid in our commitment in the mutual defense treaty we have with the Philippines. That hasn't changed," he said, adding that he hoped the alliance would "grow and develop and deepen."
Associated Press