The area of sea identified is some distance from the Paracel islands and even further from the Spratlys, with both chains claimed by Beijing and several other neighbouring states.
The Permanent Court of Arbitration (PCA) in The Hague last week ruled that there was no legal basis for Beijing’s claims to much of the sea, embodied in a “nine-dash line” that dates from 1940s maps and stretches close to other countries’ coasts.
Manila — which lodged the suit against Beijing — welcomed the decision, as China dismissed it as a “piece of waste paper”.
Despite Chinese objections, the European Union weighed in on the subject at a regional summit this weekend, with President Donald Tusk telling reporters that the grouping “will continue to speak out in support of upholding international law”, adding that it had “full confidence” in the PCA and its decisions.
China pressured countries in the ASEAN bloc of Southeast Asian nations not to issue a joint statement on the ruling, diplomats said.
Beijing held military drills in the South China Sea just days before the international arbitration court ruling, state media reported.
China has rapidly built reefs in the waters into artificial islands capable of military use.
In a separate message on its website, the maritime administration said last week that four out of five lighthouses built atop islands and reefs in the sea have been activated, and a fifth would be put into use soon.