Indian officials say a naval vessel on a trip to Vietnam was warned by China that it was allegedly violating Chinese waters.
India's foreign ministry said Thursday the INS Airavat was sailing about 45 nautical miles off the coast of Vietnam on July 22 when a caller identifying himself as the Chinese navy made radio contact and told the Indian vessel: "You are entering Chinese waters."
The foreign ministry said no ship or aircraft were visible and that the Airavat continued its journey.
China has grown more assertive _ and at times aggressive _ in pressing its claims to much of the South China Sea, aided by a buildup of its navy. Chinese ships have rousted fishing vessels from Vietnam and the Philippines, both of which contest China's claims.