Welcoming his Vietnamese counterpart to Manila, Filipino defence secretary Gilberto Teodoro acknowledged the two Southeast Asian nations had "bilateral issues", but said they were working together to overcome their "common threats".

Teodoro announced they would sign a "memorandum on defence cooperation within this year" to "continue and enhance cooperation in the naval, air, army and land force spheres".

Vietnam and the Philippines both contest the Spratly Islands in the South China Sea, but have increasingly sought to shore up ties as Beijing claims almost the entire disputed waterway.

Vietnamese Defence Minister Phan Van Giang's three-day visit to Manila follows a port call and joint firefighting and search-and-rescue exercises in the Manila Bay this month.

Phan said the two sides would work together on "disaster response and search and rescue, military medicine, cybersecurity, defence industry" and other matters.

"The alliance between the Philippines and Vietnam is strong," Teodoro later told reporters.

Phan also met with Philippine President Ferdinand Marcos on Friday to discuss defence, trade and maritime cooperation, according to a presidential palace statement.

Marcos said the visit would further promote "the depth and range of our relationship".

"Together, we remain committed to peaceful resolutions, de-escalating tensions and ensuring that the rule of law and a rules-based international order prevail in our region," Marcos said in a separate post on social media.