The Armed Forces of the Philippines is validating information that about 2,000 to 3,000 Chinese soldiers are in the country, calling it a “matter of serious concern.”

“I have my staff for intelligence to confirm said reports in coordination with other relevant agencies of government,” Gen. Felimon Santos Jr., AFP chief of staff, said in a statement.

Senator Panfilo “Ping” Lacson, a former national police chief, earlier disclosed that a reliable source told him about the presence of up to 3,000 members of the Chinese People’s Liberation Army. The source said the foreign troops seem to be “on an immersion mission.”

Lacson called on intelligence authorities to “exert exra effort to gather information” on the matter.

This is a developing story