Japanese former residents of a group of Russian-controlled islands off Hokkaido flew to two of the disputed isles Saturday to visit their ancestors' graves, in the first such air trip negotiated during a decades-long territorial spat.

The group was able to visit the graves in the islands of Kunashiri and Etorofu on Saturday as planned, according to the Japanese Foreign Ministry. The former residents were scheduled to return to Japan later in the day, but are expected to do so Sunday due to bad weather.

As a chartered plane departing Etorofu could not land in Kunashiri, it arrived in Yuzhno-Sakhalinsk of Sakhalin instead.

As a result, some of the group are likely to stay night in Kunashiri and Sakhalin.

The trip by the group of 68 people, including 17 former islanders and their families, was originally scheduled in June but postponed due to poor weather.

Until now, there have only been trips by chartered ship during the summer to the islands, seized by the Soviet Union after Japan surrendered in World War II in August 1945.

The islands of Etorofu, Kunashiri, Shikotan and the Habomai islet group are collectively called the Northern Territories in Japan and the Southern Kurils in Russia. The territorial row has prevented Japan and Russia from concluding a postwar peace treaty.

The arrangement for the day trip to Etorofu and Kunashiri is in line with a bilateral agreement struck between Prime Minister Shinzo Abe and Russian President Vladimir Putin in April to reduce the burden on the aging former islanders.

Abe, who is expected to dissolve the House of Representatives next week for an election, hopes the trip will enable him to emphasize his accomplishments as a leader.

But the trip is unlikely to lead to progress in the territorial dispute as Moscow only accepted it on humanitarian grounds.

"It would be great if the visit could accelerate talks (between Russia and Japan) but honestly it has nothing to do with territorial negotiations," said a Japanese Foreign Ministry official.