Trade ministers from 12 countries continued negotiations on the proposed Trans-Pacific Partnership on Thursday, with outstanding issues proving to be more difficult than expected.

Ministers were hoping to announce the outcome of the talks at a joint news conference planned for Friday afternoon following the four-day meeting. But the participating countries are still at odds over intellectual property, liberalization of dairy products and tariffs, among other issues.

Economic and Fiscal Policy Minister Akira Amari, who is in charge of the country's talks concerning TPP, told reporters that the start of Thursday's plenary session was pushed back a few hours due to a conflict among negotiators of each country over the issue of monopolies on pharmaceuticals, seen as the biggest sticking point.