The United States is criticizing new Chinese provincial regulations that aim to restrict fishing by foreign vessels in disputed areas of the South China Sea.
Under the rules passed by China's southernmost province of Hainan, all foreign fishing boats must seek permission before entering waters claimed by Beijing.
The law, which went into effect January 1, covers more than half the 3.5 million square kilometer South China Sea, including parts claimed by the Philippines and Vietnam.
U.S. State Department spokeswoman Jen Psaki said Thursday the move will raise tensions in the sea, which has seen a rising number of small-scale clashes in recent years.
Psaki said, "The passing of these restrictions on other countries' fishing activities in disputed portions of the South China Sea is a provocative and potentially dangerous act."
Psaki said it is the longstanding U.S. position that all sides avoid "unilateral action that raises tensions and undermines the prospect for a diplomatic or other peaceful resolution of differences."
The Philippines has said it is seeking more information about the regulations, while Vietnam responded by emphasizing its own claims in the energy-rich area.
Chinese Foreign Ministry spokeswoman Hua Chunying defended the move as unremarkable.
"China is a maritime nation, so it is totally normal and part of the routine for Chinese provinces bordering the sea to formulate regional rules according to the national law to regulate conservation, management and utilization of maritime biological resources," said Hua.
Sam Bateman, a senior fellow at the S. Rajaratnam School of International Studies in Singapore, tells VOA if Beijing were to follow through with the restrictions, there is a "good chance" of heightened tensions.
But he says it would be difficult for China to enforce the policy because of the massive effort needed to patrol the area.
Bateman said, "This is not just surface ships, but also air surveillance of the area, because normally maritime surveillance and fishery surveillance of that nature is primarily carried out by air and then you use surface vessels to respond to any suspicious sighting."
Bateman, a retired rear admiral in the Royal Australian Navy, says the regulations go "beyond anything acceptable under the International Law of the Sea," making China vulnerable to legal challenges.
"I think if China tried to start enforcing the regulation, and particularly if it arrested a vessel, it would run fairly quickly into a legal dispute, which frankly I don't think China would have any chance at all of winning," said Bateman.
An official representing Vietnamese fishermen said his country will lodge a protest against China's latest move in the disputed South China Sea.
Vo Van Trac, Vice Chairman of Vietnam Association of Fishery, told VOA's Vietnamese service that Vietnamese fishermen strongly oppose China's rules and will continue fishing in areas in the South China Sea where Vietnam also claims sovereignty.
He said, "The rules will obviously have an impact on our fishermen's lives. We will ask our fishermen to keep fishing. We will tell them those areas [in the South China Sea] that are within our sovereignty. The most important thing right now is to reassure them about that".
China's claims in the South China Sea overlap with those of ASEAN members Vietnam, the Philippines, Malaysia and Brunei. All four are seeking multilateral talks to resolve the disputes. But Beijing has said it will only hold one-on-one negotiations.
The U.S. says it does not take a position on the sovereignty disputes, but has consistently criticized Chinese moves it calls aggressive. Washington has also expanded military alliances with Southeast Asian nations involved in the disputes.
The fishing rules follow China's announcement last year of a new Air Defense Identification Zone (ADIZ) over disputed waters in the East China Sea. The zone has drawn criticism from Japan, South Korea and the United States.
Analysts are now debating whether China will declare a similar ADIZ in the East China Sea.