China, Japan, and South Korea are expected to agree on the launch of three-way free trade talks at a summit in the Cambodian capital this week, Beijing's foreign ministry spokesman said Sunday.

"I am optimistic the three parties can reach a consensus to commence the negotiations," Qin Gang told reporters in Phnom Penh where leaders of the three nations will attend an East Asia Summit from Monday.

Qin said trade ministers were likely to hold a trilateral meeting on the matter on the sidelines of the gathering despite a recent spike in tensions between Tokyo and its neighbours over two separate maritime rows.

"Hopefully we will have a positive announcement," Qin said. "But I don't have a timetable to offer for when the three countries complete the negotiations."

While ministers may be able to set aside maritime disputes to talk about trade, a Japanese diplomat said on Wednesday there are no plans for a customary Japan-China-South Korea leaders' meeting during the summit.

Beijing and Tokyo are squabbling over the sovereignty of an archipelago in the East China Sea, while Japan and South Korea are in dispute over who owns a pair of islets in waters between the two countries.

The leaders of the three East Asian giants have held the three-way talks almost every year since 1999 on the sidelines of the regional get-together.

Qin said for Sino-Japanese ties to improve, the "Japanese government has to take a right policy about China."

"Particularly on those important issues relating to territorial sovereignty of China. Only by having by good policies and handling these sensitive issues properly can we have better prospects of China-Japan relations," he added.

Japan, China and South Korea depend on each other for about 20-30 percent of their external trade, according to the business daily Nikkei.

If the trilateral FTA is concluded with the easing of tariffs on manufactured and other goods, Japan's exports are expected to increase by $60 billion, Nikkei said.