New evidence has emerged that China's state-owned fishing fleet may be a front for covert intelligence operations in the disputed waters of the South China Sea.
An investigation by Radio Free Asia has linked a fleet operating out of Woody Island in the contested Paracel archipelago to projects involving national security information, suggesting that the ships are engaged in activities beyond fishing.
China has long denied the accusation that its maritime militia have been secretly embedded into the nation's fishing fleet to intimidate and squeeze out rival Asian claimants to waters that are criss-crossed by important international shipping routes.
RFA also discovered that one of the ships operating out of Sansha City on Woody island, was used to test an experimental command and communications system built with foreign technology.
It reported that this likely transformed the vessel into a mobile communications and surveillance platform capable of transmitting intelligence back to the authorities on land.
The investigation revealed that numerous "fishermen" living in Sansha are actually militiamen responsible for guarding China's outposts.
It established that Sansha's maritime militia had been created in 2013 and by 2016 had expanded to include over 1800 personnel and more than 100 vessels in a fleet that the Sansha city government described as playing an "irreplaceable role" in defending China's maritime claims.
China is beefing up its presence in the strategic South China Sea, raising fears it is working to seize control of access to shipping routes to be used for possible economic coercion.
It has also been accused of militarising reefs, atolls and waters that are claimed by other nations. Vietnam also views the Paracel islands as its own territory.
To expand its territorial claims, China has deployed its navy, coastguard and its maritime militia - dubbed China's "Little Blue Men", in reference to the unmarked Russian "Little Green Men" soldiers who appeared in Crimea shortly before President Vladimir Putin annexed the peninsula.
The militia is embedded into China's fishing fleet to intimidate and squeeze out rival South East Asian claimants to the waters.
In recent weeks, the Whitsun Reef claimed by the Philippines became a flashpoint after more than 200 Chinese vessels anchored there, defying diplomatic protests from Manila and the US. China has denied all charges, insisting the vessels were fishing boats anchored in the area to shelter from rough seas.