TOKYO (APP)- China, Japan and South Korea will sign a treaty in May to boost cross-border investment and better protect intellectual property, a report said here on Sunday. The deal is expected to be sealed when leaders of the three countries meet in Tokyo, four years after negotiations were launched, the Nikkei said, stepping up cooperation between nations that have not always enjoyed easy ties. The trilateral accord adds to existing bilateral investment deals among the three, the Nikkei said. Under the existing Japan-China investment accord, Japanese companies have to rely on Chinese laws to protect their intellectual property. The planned trilateral deal would enable settling intellectual property disputes under international frameworks, the newspaper said. It would also allow companies to demand a clear explanation when the Chinese government applies or changes its law in an opaque manner, the Nikkei said. The three nations are expected to reach a broad agreement before the May summit, it said, adding that they will seek to bring the accord into effect by the end of 2012. Separately, the three nations will continue studying the possibility of forming a trilateral free trade agreement, the newspaper added. An investment deal is easier to negotiate than a free trade agreement, which liberalises a wide range of areas from tariffs to customs procedures.