Philippine President Rodrigo Duterte said he was giving notice to the United States, his country's long-standing ally, that joint exercises of Filipino and US troops next week will be the last such drills.

He told the Filipino community in Hanoi late on Wednesday night that he will maintain the military alliance with the US because of the countries' 1951 defense treaty. But added next week's exercises will proceed only because he did not want to embarrass his defense secretary.

Duterte said during a two-day visit to meet Vietnam's leaders that he wants to establish new trade and commercial alliances with China and Russia.

"I would serve notice to you now that this will be the last military exercise," he said. "Jointly, Philippines-US, the last one."

"I will maintain the military alliance because there is an RP-US pact which our countries signed in the early '50s," he said, referring to the Republic of the Philippines. "I will establish new alliances for trade and commerce and you are scheduled to hold war games again, which China does not want."

The Philippine-US Amphibious Landing Exercises are set to take place from Oct 4 to 12 in the Philippines, which follow the larger annual Balikatan exercises in April involving 8,000 forces from both sides.

Duterte has had an uneasy relationship with the US since he won a presidential election in May. He said he is charting a foreign policy not dependent on Washington.

Earlier this month, he said he would not allow government forces to conduct joint patrols of disputed waters near the South China Sea with foreign powers, apparently scrapping a deal his predecessor reached with the US military earlier this year.

He has said he wants US military forces out of the southern Philippines and blamed Washington for inflaming Muslim insurgencies.

Duterte has said he was considering acquiring military equipment from Russia and China.