Beijing expressed opposition on Wednesday to a Japanese initiative led by the country's ruling party that aims to draw up an act that would "lay the legal basis"to foster ties between Tokyo and Taiwan.

"We firmly oppose the attempt to institute a so-called Japanese version of the Taiwan Relations Act by some Japanese lawmakers to strengthen ties with Taiwan,"said Foreign Ministry spokeswoman Hua Chunying.

Analysts said evidence shows that such an act — likely to implicitly outline Taiwan as a "sovereign state"— is not something produced overnight but an agenda resulting from years of deliberation.

They said it would profoundly challenge the relationship between China and Japan and undermine the already-improving cross-Straits situation.

The Japanese initiative was disclosed after lawmakers from the Liberal Democratic Party held a meeting on Monday to formulate a plan for an act similar to that drawn up by the United States in 1979 to "lay the legal basis for stronger economic relations and personal exchanges with Taiwan”, Japan's Kyodo News Agency said.

The lawmakers are members of an association of junior lawmakers dedicated to the promotion of economic and cultural exchanges between Japan and the island. The association is chaired by Nobuo Kishi, the Japanese deputy foreign minister and younger brother of Prime Minister Shinzo Abe.

"Deliberation of the act is actually a step that calls for a high alert,"said Liang Yunxiang, a professor of Japanese studies at Peking University.

Signed in 1979 by then-US president Jimmy Carter, the US Taiwan Relations Act has long been opposed and never recognized by the Chinese government. The unilaterally drafted act promised US military engagement if a cross-Straits war breaks out. Beijing also has opposed US arms sales to Taipei based on this act.

According to the 1972 China-Japan Joint Statement, the Japanese government says it fully understands and respects the Chinese government's position on Taiwan as an inalienable part of Chinese territory.

"The Taiwan question concerns China's fundamental interests. It also concerns the political foundation of China-Japan ties in handling Japan-Taiwan relations,"Hua of the Foreign Ministry said.

Gao Hong, a senior expert at the Institute of Japan Studies at the Chinese Academy of Social Sciences, said, "The Taiwan question has always been a highly sensitive topic that concerns the basis of China-Japan diplomatic relations."

Kishi, the Japanese deputy foreign minister, is an advocate of such a bill.

His legislative intentions were underlined in his article in the November issue of the Japanese monthly magazine Seiron, in which he said, "It is a top priority to rebuild the Japan-Taiwan relationship.”

Frank Hsieh, former head of Taiwan's opposition Democratic Progressive Party, hailed the idea of drafting such an act during his lecture on Dec 2 at the University of Tokyo, saying that "Japan has the capability"to do so, following the lead of the US, Japan's Searchina website reported.

Former Taiwan leader Lee Teng-hui, who advocated the idea of an "independent Taiwan”, echoed Kishi's idea in an interview with a Taiwan newspaper in January, saying that designing a Japanese version of the Taiwan Relations Act is an unfinished mission for Tokyo.

Zhang Lili, director of the Center of Chinese Diplomacy Studies at China Foreign Affairs University, said the legislative campaign shows Japan's ulterior motive to undermine cross-Straits relations at a time when China-Japan ties have been deadlocked over territorial and historical issues.

"Japan is seeking to contain China in this regard, and does not want to see prosperity and reunification across the Straits,"Zhang said.

Japan's Sankei Shimbun newspaper confirmed that officials from the Japanese Foreign Ministry attended Monday's meeting. It said they briefed the lawmakers about the situation regarding Taiwan and on the negotiation progress of the so-called Japan-Taiwan fishery pact.