A US Congressional report said Washington has never recognized Japan's sovereignty over the Diaoyu Islands and takes no position over the territorial row between Japan and China.

The report, published on Sept 25 by the Congressional Research Service, said the US recognizes only Japan's administrative power over the Diaoyu Islands after the Okinawa Reversion Treaty was signed in 1971.

China-Japan relations hit the lowest point in years after Tokyo's so-called purchase of the Diaoyu Islands on Sept 10, a move sparking wide protest across China. The islands have been Chinese territory for centuries.

During Senate deliberations on whether to consent to the ratification of the treaty, the US State Department asserted that the US took a neutral position with regard to the competing claims of Japan and China, despite the US' return of the islands to Japanese administration.

"Department officials asserted that reversion of administrative rights to Japan did not prejudice any claims to the islands," said the report from the Congress' think tank, the public-policy research arm of the US Congress.

Chinese Foreign Ministry spokesman Hong Lei on Monday said he noted the US' neutral position on the Diaoyu Islands in the report and added he hopes the US will "walk the talk".

Analysts said the report, which reflects the Obama administration's stance over the territorial row between its ally and China, is an effort to ease the escalating tension but can hardly change the US' Japan-tilt policy.

However, according to the report, the Diaoyu Islands fall under the scope of the 1960 US-Japan Security Treaty since 1972, which stipulates that the US is bound to protect "the territories under the administration of Japan".

Under the treaty, the US guarantees Japan's security in return for the right to station US troops — about 50,000 — in dozens of bases throughout the Japanese archipelago.

Washington has been ambiguous on the Diaoyu Islands issue as it supports Tokyo with the US-Japan Security Treaty, but has warned Tokyo not to break the "red line" of China or cause large-scale conflicts, said Feng Wei, an expert on Japanese studies at Fudan University in Shanghai.

Both Japan and the US have made some compromises in front of China's all-round countermeasures over the issue, and "Washington is especially worried that the China-Japan territorial dispute could threaten US and Japan's economy as well as the Asia-Pacific stability amid its strategic pivot to the region", he said.

On Friday, Japanese Foreign Minister Koichiro Gemba delivered a written statement to Taiwan saying that the Japanese government hopes to resume talks on fishing in the waters in the East China Sea.

But at the same time, two US aircraft carrier strike groups have been deployed since mid-September to the Western Pacific in an apparent attempt to keep the activities of the Chinese military in check and as a response to China's launch of its first aircraft carrier at the end of September, Japan's Yomiuri Shimbun said on Oct 6.

Hong told a regular news conference that Chinese marine surveillance ships and fishery patrol ships will continue their official duties in waters near the Diaoyu Islands, which are under China's jurisdiction.

Fishery authorities said on Saturday that five fishery patrol ships were in the area during the National Day holiday from Sept 30 through Sunday to continue their patrol missions. Four Chinese marine surveillance ships also arrived in the waters on Oct 2.

"Safeguarding China's territorial sovereignty and maritime rights and interests is the Chinese military's sacred duty," Hong said.

He also once again urged Tokyo to correct its mistakes and return to negotiations to resolve the dispute, as well as to strictly comply with the one-China policy and properly handle relevant issues.

In sensitive situations like this, favoring one party helps little in de-escalating a potentially violent conflict, Mike Honda, a Japanese-American and US representative for California, said on his blog earlier this month.

"If this conflict becomes violent on the East China Sea, we will see shipping thwarted, more factories closed, costs of imports climb and other foreign policy decisions affected," he said.