Lawmakers in the Philippines are seeking an investigation into a secret US military propaganda operation, Reuters, reported on Friday.

The alleged propaganda sought to raise doubt among Filipinos about China's vaccines during the COVID pandemic.

Philippine senator Imee Marcos, who chairs the foreign relations committee and house representative France Castro, filed resolutions in the Congress to initiate the probe, according to documents Reuters has reviewed.

The Pentagon is claimed to have run a clandestine campaign in 2020 and 2021 to raise concerns against the Sinovac vaccine and other pandemic aid from China.