The 60-year-old dispute over four southern islands annexed by the Soviet Union at the end of the Second World War has prevented Russia and Japan from signing a peace treaty that would formally end their WWII hostilities, and has been a major obstacle to closer cooperation between the two nations in areas such as energy.
Addressing parliament Wednesday, Taro Aso said splitting the islands by total area in two equal halves would give Japan a quarter of the largest, northernmost island, Etorofu, and the three smaller ones.
Tokyo has long insisted that all four islands must be returned, and analysts said the idea of allowing Russia to retain control over 75% of Etorofu is unlikely to be accepted by either the ruling elite or the public.
During the Soviet era, the Japanese government rejected a Russian plan to divide the islands by number, with the two southernmost islands going to Tokyo and the remaining two to Moscow.
Alexander Konovalov, director of Russia's Institute for Strategic Assessments and Analysis, said the proposal could pave the way for a breakthrough in stalled talks over the Kurils.
But Elgena Molodyakova, who heads Russia's Association of Japan Scholars, argued that the initiative is just an attempt to probe the Russian side's stance on the issue, and should not be treated as a realistic option.
"A lot of work will have to be done to [prepare] public opinion," she said. "Without such work, the idea of splitting the islands has no future."
In a statement issued Thursday, the Foreign Ministry said Aso's suggestion should not be viewed as an official proposal on the part of the Japanese government, but only as a display of its willingness to resolve the territorial dispute with Russia sooner rather than later.
Speaking to RIA Novosti on condition of anonymity, a source in Japan's ruling Liberal Democratic Party said Aso's proposal was made in line with Tokyo's overall goal of reaching a mutually acceptable solution to the territorial dispute and signing a peace deal with Russia.
He said the government is now facing strong criticism from the opposition for lack of progress in that area.
Aso said Japan should try to overcome the impasse over the Kurils before the end of Russian President Vladimir Putin's term in office in 2008, given the incumbent's strong political positions and his willingness to resolve the dispute.