Police in the southern Chinese island province of Hainan will board and search ships which enter into what China considers its territorial waters in the disputed South China Sea, state media said.
The South China Sea is Asia's biggest potential military trouble spot with several Asian countries claiming sovereignty.
From January 1, Hainan police will have the authority to board and seize control of foreign ships which "illegally enter" Chinese waters and order them to change course or stop sailing, the China Daily reported.
"Activities such as entering the island province's waters without permission, damaging coastal defence facilities and engaging in publicity that threatens national security are illegal," the English-language newspaper said.
"If foreign ships or crew members violate regulations, Hainan police have the right to take over the ships or their communication systems, under the revised regulations," it added.
China's assertion of sovereignty over the stretch of water off its south coast and to the east of mainland Southeast Asia has set it directly against Vietnam and the Philippines, while Brunei, Taiwan and Malaysia also lay claim to parts.
China occasionally detains fishermen, mostly from Vietnam, who it accuses of operating illegally in Chinese waters, though generally frees them quite quickly.
Hainan, which likes to style itself as China's answer to Hawaii or Bali with its resorts and beaches, is the province responsible for administering the country's extensive claims to the myriad islets and atolls in the South China Sea.
The newspaper said that the government will also send new maritime surveillance ships to join the fleet responsible for patrolling the South China Sea, believed to be rich in oil and gas and straddling shipping lanes between East Asia and Europe and the Middle East.
The stakes have risen in the area as the U.S. military shifts its attention and resources back to Asia, emboldening its long-time ally the Philippines and former foe Vietnam to take a tougher stance against Beijing.
China has further angered the Philippines and Vietnam by issuing new passports showing a map depicting China's claims to the disputed waters.