China, Japan and South Korea have reached a trilateral investment agreement, bringing to fruition over a decade of efforts to bridge Asia's three leading economic powers and advance the ultimate goal of a free-trade zone.

The conclusion of the negotiations gives impetus to discussions over a free-trade agreement between Japan, China and South Korea, Japan's Ministry of Economy, Trade and Industry said in a statement Thursday, according to the Wall Street Journal.

The details of the agreement remain unknown, but will become clear at the official signing expected at a summit in May. It would be the first legal economic agreement among the three nations.

The deal is expected to increase government transparency, dispute resolution and intellectual property rights protections in China.

The agreement's signing has been interpreted as a first step towards a free-trade agreement between the nations, though it may take years, a senior Japanese official told the Journal. South Korean President Lee Myung-bak and Chinese leader Hu Jintao agreed in January to start formal discussions for a free trade agreement by June.