Philippine President Rodrigo Duterte has told his foreign minister to give formal notice to the United States of his termination of a Visiting Forces Agreement (VFA) between their militaries, his spokesman said on Tuesday.

Duterte, who has openly disapproved of the two countries' military alliance, made the decision after a close ally said his visa for the United States had been rescinded, in an issue related to the president's war on drugs.

"It's about time we rely on ourselves, we will strengthen our own defences and not rely on any other country," Duterte's spokesman Salvador Panelo told a regular briefing, quoting the president.

The Visiting Forces Agreement (VFA), signed in 1998, accorded legal status to thousands of US troops who were rotated in the country for military exercises and humanitarian assistance.

The two countries also have a Mutual defence Treaty and an Enhanced Defence Cooperation Agreement (EDCA), which remain in place.