FILE PHOTO: A seagull flies above the waters of the Pacific Ocean near the Island of Kunashir, one of four islands known as the Southern Kuriles in Russia and the Northern Territories in Japan, December 20, 2016. REUTERS/Yuri Maltsev

MOSCOW (Reuters) - The Kremlin said on Tuesday that talks with Japan aimed at clinching a World War Two peace treaty between the two countries and ending a territorial dispute over a chain of islands in the Pacific could go on for years and were complex.

Japan has been mounting a push to resolve the dispute over four islands - known as the Northern Territories in Japan and the Southern Kuriles in Russia - which has prevented Moscow and Tokyo from formally ending their World War Two hostilities.

Prime Minister Shinzo Abe has been holding regular talks with President Vladimir Putin to end the decades-old dispute, but so far without a breakthrough.