China's amendments to its fishing rules aim to enhance management of its administrative waters in the South China Sea, and will not hamper freedom of navigation or regional security, observers said.

"The concepts of the South China Sea — international waters and waters under Chinese jurisdiction vary in terms of their implications," said Wu Shicun, president of the National Institute for South China Sea Studies.

The South China Sea covers 3.55 million square km, while China exercises jurisdiction over about 2 million square km of it, Wu said.

"It is natural that coastal provinces forge local regulations in line with state laws to develop and protect biological resources in governed waters," he said.

Since Jan 1, new fishing rules in Hainan province require foreign vessels entering its administrative waters for fishing or related surveys to seek permission from departments under the State Council.

The rules allow confiscation of catches and fishing equipment as well as fines of up to 500,000 yuan ($82,800). Those who commit crimes will be investigated.

Wu said China's claim — defined by the South China Sea "nine-dash line" — was established long before the United Nations Convention on the Law of the Sea took effect. In accordance with the intertemporal law, the nine-dash line should be recognized by the international community, Wu said.

"The waters that China claims had been under Chinese jurisdiction long before the United Nations Convention on the Law of the Sea was established (in 1982), and therefore should be taken into consideration," he added.

The Foreign Ministry and Hainan officials said the new rules protect local fisheries resources. Calling the rules routine for an ocean state, ministry spokeswoman Hua Chunying said the goal is to strengthen the security of fisheries resources.

Li Guoqiang, a research of Southeast Asian studies at the Chinese Academy of Social Sciences, said the rules, created with the purpose of managing fisheries production, do not target any specific country, so they will not challenge free navigation in the area.

"The new regulation contains 41 articles, most of which prescribe requirements for domestic fishing activities. Only one article applies to foreign incomers, and it conforms with international law," Li said. "Therefore, allegations calling the law a threat to regional stability are totally groundless."

The new rules, approved in late November, drew immediate criticism from some other countries in the area, including Vietnam and the Philippines.

Manila said on Friday that the rules "escalates tensions, unnecessarily complicates the situation in the South China Sea, and threatens regional peace and stability". Hanoi also voiced opposition, urging Beijing to abolish the "illegal" rules.

Experts said that despite China's restraint and constructive attitude to facilitating dialogue, the situation in the South China Sea is complicated by certain countries' uncooperative stances along with increasing intervention from Washington.

On Thursday, US State Department spokeswoman Jen Psaki said the South China Sea fishing rules are "provocative and potentially dangerous". Japan continued the criticism on Sunday, with Defense Minister Itsunori Onodera saying the rules left the international community jittery.

Zhuang Guotu, director of the Southeast Asian Center at Xiamen University, said the regulation is only a timely revision of China's fisheries law, which has been in effect since 1986, and that other countries have no right to criticize it.

The fact that Washington and Tokyo have recently complained about a Chinese regulation that has been in place for decades is only a continuation of their usual practice of treating China as a threat, Zhuang said.

"The US, in the Western Hemisphere, came to judge China's policies in the South China Sea, but the fact is, China never set barriers for safe passage in international waters while the White House never has given a reasonable explanation for its military presence in the region," he added.

Contact the writers at [email protected] and [email protected]

Zhang Yan and Xinhua contributed to the story.