Beijing claims much of the waters and has put a vast swathe of it under the administration of Sansha city, in the contested Paracel islands, which also hosts a military garrison.
Local authorities will "provide a 5,000-tonne patrol vessel at Sansha and gradually set up a system of three regular patrols", China Ocean News reported, citing an agreement between the city and the island province of Hainan, which oversees it.
The intent was to "safeguard national sovereign rights and benefits, develop at-sea assistance, ensure navigational safety" among other reasons, the report said.
Portions of the South China Sea are also claimed by the Philippines, Vietnam, Malaysia, Brunei and Taiwan.
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Earlier this month both the US and Philippines criticised a law approved in Hainan in November reaffirming an existing requirement that foreign fishing vessels obtain permission to enter its waters.
China also declared in November an Air Defence Identification Zone over parts of the East China Sea -- including the islands disputed with Japan -- provoking vehement condemnation from Tokyo and Washington.