BEIJING (Reuters) - China’s Supreme Court said on Tuesday people caught illegally fishing in Chinese waters could be jailed for up to a year, issuing a judicial interpretation defining those waters as including China’s exclusive economic zones.

A fisherman repairs his boat overlooking fishing boats that fish in the disputed Scarborough Shoal in the South China Sea, at Masinloc, Zambales, in the Philippines April 22, 2015. REUTERS/Erik De Castro

An arbitration court in the Hague ruled last month that China had no historic title over the waters of the South China Sea and that it had breached the Philippines’ sovereign rights with various actions in the sea, infuriating Beijing, which dismissed the case.

None of China’s reefs and holdings in the Spratly Islands entitled it to a 200-mile exclusive economic zone, the court decided.

China’s Supreme Court made no direct mention of the South China Sea or the Hague ruling, but said its judicial interpretation was made in accordance with both Chinese law and the U.N. Convention on the Law of the Sea (UNCLOS), under which the Philippines had brought its case.

“Judicial power is an important component of national sovereignty,” the Supreme Court said.

“People’s courts will actively exercise jurisdiction over China’s territorial waters, support administrative departments to legally perform maritime management duties ... and safeguard Chinese territorial sovereignty and maritime interests.”

Jurisdictional seas covered by the interpretation include contiguous zones, exclusive economic zones and continental shelves, it said.

People who illegally entered Chinese territorial waters and refused to leave after being driven out, or who re-entered after being driven away or being fined in the past year, would be considered to have committed “serious” criminal acts and could get up to a year in jail, the Supreme Court said.

“The explanation offers legal guarantees for marine fishing law enforcement,” it added.

China’s defense minister Chang Wanquan warned of offshore security threats, especially threats from the sea, and said China should prepare for a “people’s war at sea” to safeguard national sovereignty, the official Xinhua news agency reported.

China claims most of the South China Sea, through which more than $5 trillion of trade moves annually. Brunei, Malaysia, the Philippines, Taiwan and Vietnam have rival claims.

China periodically detains fishermen, especially from the Philippines and Vietnam, and Chinese fishermen also occasionally get detained by other claimants in the South China Sea.

Separately, China’s military has inaugurated a memorial to servicemen who died in 1974 clashes with South Vietnamese forces that resulted in China cementing its rule over the Paracel Islands, the People’s Liberation Army Daily said.

The memorial, on Duncan Island, commemorates the 18 Chinese who died, the paper added.