Countries involved in the Trans-Pacific Partnership free trade initiative have set a target of concluding negotiations on some issues by the end of the year, despite failing to fix a time line for the most contentious areas, including tariffs, sources close to the negotiations said.

Based on a "joint work plan" developed by their trade chiefs, the 12 TPP member nations, including Japan and the United States, now aim to end part of the negotiations on reform of state-owned firms, the environment and intellectual property by year's end, according to the sources.

The plan was drawn up at a TPP ministerial meeting in Beijing on Nov. 8 to accelerate the seemingly interminable negotiations. The ministers did not elaborate on its content.