South Korean fishing boats have moved into waters off the disputed Kuril islands, despite a growing diplomatic row with Japan.

The Kuril islands were seized by Russia from Japan at the end of World War II, but Japan claims sovereignty over them.

Russia has granted South Korea permits to fish there, but Japan says that undermines its territorial claim.

On Monday South Korean and Japanese negotiators failed to resolve the dispute after two days of talks.

Russian permits

South Korea says it is acting from a commercial view and that fishing has nothing to do with the territorial dispute. But Tokyo sees the Kuril waters at part of its exclusive economic zone.

By early Tuesday, 26 South Korean boats with 13 Russian inspectors aboard had reached the waters off the Kurils, said South Korea's Maritime Affairs and Fisheries Ministry.

Under an agreement signed by Russia in December, the 26 boats are allowed to fish until 15 November and catch 15,000 tons of saury worth $23m.

The permits came into effect on 15 July, but South Korea delayed the start of the fishing because of low water temperatures that inhibit saury from gathering.

Textbook row

On Monday Japanese officials said Tokyo would lodge official complaints with Seoul and Moscow if South Korea started fishing in the area.

The two countries have been at loggerheads over the issue since mid-June.

In protest, Japan last month postponed granting licences to South Korean boats to fish off the Japan's north-east Honshu island.

Japan has been in talks with Russia to take back the Kuril islands but no agreement has been reached.

The fishing dispute with South Korea is the latest issue to cause friction between the neighbours. South Korea is angry at Japan's decision to approve the use of a history textbook that it says glosses over Japan's wartime atrocities.

Two countries have been trying to improve relations for years - next year they are co-hosting the football world cup.