Japan has made a bilateral proposal to scratch tariffs on nearly 90 percent of U.S. imports under the 12-member Trans-Pacific Partnership talks, an informed source said Wednesday.

The percentage of tariff-free items would thus top the 88.4 percent that Japan agreed to eliminate within 10 years for the Philippines — the highest so far among the 13 free trade agreements Japan has concluded.

If Japan eliminates all tariffs except for the sensitive categories of rice, beef, pork, dairy products and sugar, the tariff-free percentage would rise to 93.5 percent.

Japan and the United States are planning to hold a bilateral session on tariffs in Washington from Friday through Monday in parallel with a chief negotiators' session on sorting TPP issues from Wednesday through Saturday.

Japan exchanged a list of tariff-free item proposals with Brunei, New Zealand, Malaysia, Mexico, Peru and Singapore at the TPP's 19th round of talks in August. The offers made at the time averaged around 80 percent.

The Japanese government is under strong domestic pressure to protect its agricultural sector. Thus, tariffs on key farm products, especially rice, were apparently excluded from Wednesday's offer.

The 12 TPP members — Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, the United States and Vietnam — are seeking to reach a basic agreement in October and conclude the trade deal by the end of the year.