Russia says, Japan's reaction towards President Dmitry Medvedev's visit, to the Kuril islands is unacceptable. The remark comes, after Japan's Foreign Ministry summoned Russia's ambassador, to lodge a protest.

Russian Foreign Minister Sergey Lavrov told a news conference on Monday that Dmitry Medvedev had the right to visit the Kuril Islands.

Russian Foreign Minister Sergey Lavrov said, "The reaction of the Japanese side to the visit of President Medvedev to the Kurils is unacceptable. This is our land and the Russian president visited Russian land, a Russian territory, a Russian region."

On Monday Medvedev became the first Russian president to visit the islands.

Japan responded with a statement opposing Medvedev's trip and called in Russia's ambassador to Japan to protest.

Japanese PM Naoto Kan said, "We have been consistent in our stance that these four northern islands are Japanese territory. I think that it's very regrettable that the president decided to visit that area."

Naoto Kan said, "It's hurt the feelings of the Japanese people. I feel it's very regrettable."

Japan's cabinet says Russia should have sent notification before the visit, and says it will protest through diplomatic channels.

The Russian President landed on Kunashiri island, one of four islands both countries lay claim to. Japan calls the islands the Northern Territories, and for Russia they are known as the southern Kurils.

The islands are surrounded by rich fishing grounds and are believed to have promising offshore oil and natural gas reserves, plus gold and silver deposits.

The islands have been under Russian control since the waning days of World War II.