US marines and members of the color guard prepare to fold their flag after the closing ceremony of the joint amphibious landing exercise with the Philippines at a military camp in Manila on Tuesday. Philippine President Rodrigo Duterte said Tuesday he would soon visit China. Photo: AFP

Philippine President Rodrigo Duterte said Tuesday he would soon visit China and hoped  also to travel to Russia, as he again criticized longtime ally the US for "arrogance."

The mission to China will be Duterte's first trip outside of Southeast Asia since assuming the presidency on June 30, in a symbolic move highlighting the importance he places on improving ties with Beijing that soured over competing claims to the South China Sea.

"China has repeatedly invited­ me. I have accepted the offer," Duterte said in a speech at the presidential palace.

He gave no specific dates for the visit, but said it would take place before he went to Japan from October 25 to 27. Manila-based Siongpo newspaper reported Sunday Duterte will visit China from October 18 to 21.

Chinese Foreign Ministry is yet to confirm the visit, but expressed Tuesday it "welcomes" his willingness to visit China.

"The two sides are in close communication," said Geng Shuang, spokesperson of ­the Foreign Ministry.

"We commend President Duterte's attachment of importance to China-Philippines relations, and believe that high-level exchanges will contribute to bilateral friendly cooperation and regional peace, stability, ­development and prosperity."

Duterte said he had originally planned to visit Japan, the Philippines' biggest source of foreign aid, ahead of China.

However he explained that Japan offered a "definite" date, then China told Duterte there was a "vacancy" earlier and so he accepted. Duterte also said that, after Japan, "Probably I will go to Russia."

Duterte has looked to build closer ties with China and ­Russia, while launching ­repeated tirades against the US, the Philippines' former ­colonial ruler and defense ally.

His tirades have been largely in response to US criticism of Duterte's war on crime, which has claimed more than 3,300 lives and raised fears about extrajudicial killings.

Duterte has canceled joint patrols with the US in the South China Sea, and said he may scrap a defense pact that allows thousands of US troops to rotate through the Philippines, and threatened to eventually cut ties completely.

He said Tuesday the Philippines gained nothing from holding military exercises with the US, which have been a mainstay of the defense ties.

Duterte had said they were to be the last of his six-year term, putting on ice the 28 exercises they hold annually.