China on Monday branded a US-Japan security treaty "a product of the Cold War" after Washington reaffirmed its commitment to Japan in its territorial dispute with China over the Senkaku Islands, known in Chinese as the Diaoyus.

The amendment, attached to the National Defense Authorization Bill, noted that while the United States "takes no position" on the ultimate sovereignty of the territory, it "acknowledges the administration of Japan over the Senkaku Islands".

It added that "unilateral actions of a third party" would not affect its position.

The legislation passed last week reaffirmed the US commitment to Japan under the Treaty of Mutual Cooperation and Security and warned that an armed attack against either party "in the territories under the administration of Japan" would be met in accordance with its provisions.

"The Chinese side expresses serious concern and firm opposition to the US Senates's amendment to the National Defense Authorization Act," foreign ministry spokesman Hong Lei told reporters.

"The Diaoyu islands and affiliated islands have been China's inherent territory since ancient times. China has indisputable sovereignty over them."

Hong said the legislation violated Washington's repeated pledge to not take sides in the dispute.

"The US-Japan security treaty is a product of the Cold War and should not go beyond the bilateral scope or undermine the interests of a third party," Hong said.

"We hope the US side will bear in mind the broader interests of peace and stability in the region, honour its words with actions and refrain from sending self-contradictory, wrong signals."

The sovereignty of the islands has been a source of friction for decades, but the row erupted earlier this year after the nationalist governor of Tokyo said he wanted to buy them for the city, forcing the Japanese government to nationalise them.

Chinese vessels have been spotted in and around the territorial waters every day for the last month.

Both sides have publicly refused to back down on their respective claims to the Japan-controlled islands.

Philippines queries China on 'board-vessels order'
Manila (AFP) Dec 3, 2012 - The Philippines has asked China to clarify reports Beijing ordered its navy to board and interdict foreign ships entering its claimed territories in the South China Sea, an official said Monday.

The foreign department said a diplomatic note seeking clarifications was sent on Saturday following reports appearing in the Chinese media, department spokesman Raul Hernandez told reporters.

"We would like China to immediately clarify its reported plans to interdict ships that enter what it considers its territory in the South China Sea," said the note, which the department posted on its website.

"If media reports are accurate, this planned action by China is... a direct threat to the entire international community.

"It violates not only the maritime domain of coastal states established under UNCLOS (United Nations Convention on the Law of the Sea), but also impedes the fundamental freedom of navigation and lawful commerce."

Hernandez said that according to reports the Chinese law would take effect in Hainan province in January 2013 and allow Chinese authorities to board, inspect, detain, confiscate, immobilise and expel vessels caught sailing through.

China claims most of the South China Sea, including waters close to the shores of its neighbours.

The claim is contested by Brunei, Malaysia, the Philippines, Taiwan and Vietnam, which have overlapping claims to some or all of those same areas.

The dispute led to a maritime standoff in April between the Philippines and China over the Scarborough Shoal.

Prior to the reports on the supposed Hainan law, China provoked fresh protests by the Philippines and Vietnam by issuing new passports that show a map including its claim to almost all the South China Sea.