China, Japan and South Korea kicked off formal negotiations Tuesday on securing a free trade agreement to bind together three economies that account for around 20 percent of global GDP.

With all three countries under new leadership, trade officials hope they can move beyond damaging territorial disputes which have dogged their relations for decades.The idea of a trilateral FTA has been on the table for decades, but diplomats say China is now pushing especially hard for a pact, in part as a counter to US initiatives in the Asia region.

Washington is leading negotiations on a Trans-Pacific Partnership (TPP) free trade pact that some see as part of the so-called US "pivot" -- aimed at reaffirming the US role in Asia in the face of China s economic rise.The TPP talks currently involve Australia, Brunei, Canada, Chile, Malaysia, Mexico, New Zealand, Peru, Singapore, the United States and Vietnam.

While China is conspicuously absent, new Japanese Prime Minister Shinzo Abe announced earlier this month Japan s decision to participate in the negotiations.The initial round of trilateral FTA talks is being held in Seoul, after which the negotiations will move to China followed by a third round in Japan, South Korean trade officials said.

China, Japan and South Korea are now Asia s largest, second-largest and fourth-largest economies, and together account for about 20 percent of global gross domestic product (GDP).Among other issues, the discussions are expected to hit opposition from Japanese farmers since a trade pact could allow cheaper agricultural products such as Chinese rice into Japan.

But the main hurdle lies in the form of bitter, long-standing territorial disputes that have raised diplomatic and military tensions and hampered economic cooperation.China and Japan are arguing about sovereignty over an archipelago in the East China Sea, while Japan and South Korea have an historic dispute over ownership of islands in waters between the two countries.