India, March 29 -- Philippine authorities have arrested six Chinese nationals and a Filipino over suspected spying on U.S. and Philippine navy vessels at the entrance of Subic Bay, a location considered as strategically crucial.

The arrests of the Chinese suspects, who officials said were posing as fishermen, brought to 12 the number of Chinese citizens taken into custody in the Philippines this year for alleged espionage, reported Radio Free Asia.

The arrests occurred amid a strained relationship between China and the Philippines over the South China Sea.

The seven suspects were arrested on March 19 after Philippine military intelligence alerted the National Bureau of Investigation about "foreign nationals suspected of carrying out co...