MANILA, Sept 14 (Reuters) - The United States may seek access to more military bases in the Philippines under a joint defence agreement between the two countries, the chief of the U.S. Indo-Pacific command said on Thursday.

The Philippines has this year increased the number of bases accessible to the U.S. military from five to nine, a move that has riled regional power China, which sees the arrangement as provocative and likely to raise tensions.

Admiral John Aquilino said he and the Philippines' military chief, Romeo Brawner, had discussed further expanding the number of bases U.S. forces could access under the Enhanced Defense Cooperation Agreement (EDCA).

"General Brawner and I made recommendations to our senior leaders for the consideration of additional sites, but there's still work to do there," Aquilino said, stressing that the U.S. was operating in the country at the invitation of the Philippines.

The closer U.S. defence ties with the Philippines after a period of decline has caused concern in China that Washington has Taiwan in mind in its efforts to boost its military presence in the region.

The United States says it intends to bolster an already strong alliance and improve the defence capability of the Philippines.

Brawner said the purpose of EDCA was training exercises and humanitarian and disaster response, key planks of a decades-old alliance between the two countries, and not related to regional security threats.

"All of this joint operations, even the selection of our EDCA sites, has nothing to do with the other countries in the Indo- Pacific region, meaning the threats that could come out from these countries," he said.

Aquilino also said the two countries were seeking to complete an agreement on boosting their intelligence sharing.