TOKYO, July 7 (RIA Novosti) - The presidents of Russia and the U.S. discussed the countries' long-running dispute over Washington's plans to deploy a missile shield in Central Europe on the first day of the G8 summit in Japan.

Leaders of the world's eight top industrialized nations have gathered at a resort on Japan's northern island of Hokkaido for talks likely to be dominated by rising food prices and the global economy.

Russian presidential aide Sergei Prikhodko said Russia's Dmitry Medvedev told George W. Bush at their one-on-one meeting that the idea of creating a missile base in post-Soviet Lithuania as an alternative to plans for Poland would be "absolutely unacceptable" to Russia.

"Dmitry Medvedev expressed his serious concern over reports periodically appearing in the media on negotiations with Lithuania on deploying missile interceptors in the country. This is absolutely unacceptable for Russia."

Moscow has strongly opposed the possible deployment by the U.S. of 10 interceptor missiles in Poland and a radar in the Czech Republic as a threat to its security and nuclear deterrence. Washington says the defenses are needed to deter possible strikes from "rogue states."

Prikhodko admitted that the discussions on missile defense had produced "no real progress," but said "working-level contacts on this problem are ongoing."

The annual summit brings together the leaders of Britain, Canada, France, Germany, Italy, Japan, Russia and the United States. This year, leaders of another 15 countries including several African states have been invited.

Japan had put climate change high on the summit's agenda, but global economic troubles and rising food prices are widely expected to overshadow other issues.