Japan has designated rice, wheat and four other agricultural products as politically sensitive items that must be protected by high tariffs in unofficial bilateral talks under the World Trade Organization, government sources said Monday.

The four other items are starch, sugar, barley and dairy products, including butter and powdered skim milk, according to the sources.

Officially, Japan says it has not discussed any individual items during WTO talks.

But in backroom vice minister-level bilateral talks under the WTO last year, Japanese officials explained that the six items are Japan's "essential crops" and "especially important in light of ensuring food security, maintaining vitality of farming villages and conserving national land," the sources said.

Japan protects other agricultural products -- such as peanuts, beans, raw silk and "konnyaku" (yams), a root used in Japanese dishes -- with high tariffs. Farmers of those products might protest their exclusion from the list of sensitive items.

During the informal bilateral talks, the United States told Japan that it will accept Japan's policy of protecting rice through minimum tariff cuts, but maintained that Tokyo should tolerate liberalization of trade in the other five items, according to the sources.

WTO members work out general rules in multilateral farm trade negotiations, but they often try to compromise on items of mutual interest in closed-door talks.

Global trade liberalization talks under the Doha Round, launched in November 2001, have been deadlocked by wide differences among member economies over key issues ranging from tariff cuts to farm subsidies.