Russia's plan to substantially increase import tariffs on automobiles before it enters the World Trade Organization has become a bone of contention for Japan, diplomatic sources here said Wednesday.

Japan has informed Russia that it cannot accept any last-minute tariff hikes, the sources said.

Russia is negotiating with key WTO member countries on its future accession to the global trade body.

During talks with Japan in Geneva in April, Russia said that before it joins the WTO, it would like to raise its import tariff rate on new vehicles to 35 percent in 2005 from the current 25 percent, according to the sources.

In May, Tokyo told Moscow that the Russian plan runs counter to the WTO's purpose of promoting free trade.

Russia's plan is intended to protect its auto industry -- one of the country's key employers. As tariff cuts will become necessary following entry into the WTO, Moscow wants to minimize the adverse effects such cuts will likely have on the auto industry by implementing tariff hikes before its accession.

Japan sees the issue as the main stumbling block in talks on Russia's entry into the WTO. Japanese automakers expect the Russian market to become a substantial source of income in the future.

The issue is expected to affect Russia's overall negotiations as other auto exporting countries, such as the United States and Germany, are indicating they back Japan.

Russia's entry into the WTO may be agreed upon in 2003 at the earliest.