Japan, China and South Korea are expected to begin negotiations next year on a trilateral accord on investment that may pave the way for a free-trade agreement by the leading East Asian economies, according to government sources.

The leaders of the three countries will likely agree on launching the talks when they get together next month at a summit with the Association of Southeast Asian Nations in the Philippines, the sources said.

An investment agreement bans unfair and discriminatory treatment against businesses within the participating countries.

The government is hoping such an accord will come to symbolize Prime Minister Shinzo Abe's efforts to improve relations with China and South Korea, the sources said.

Ties with China and South Korea have soured due mainly to the annual visits by Junichiro Koizumi to Yasukuni Shrine.

The three governments broadly agreed on an early start to negotiations for a trilateral investment agreement when Abe visited China and South Korea in early October following his installation as prime minister.

Japan has bilateral investment agreements with China and South Korea.