Russian State Duma speaker Sergey Naryshkin talks to Chairwoman of the Federation Council Valentina Matviyenko (L) during a joint meeting of the chambers of Russia's parliament to discuss the fight against terrorism, in Moscow, Russia November 20, 2015. REUTERS/Maxim Zmeyev

TOKYO (Reuters) - Moscow cannot give up disputed Pacific islands to Japan, and no talks are underway for a possible handover, the head of Russia’s upper chamber of parliament said on Tuesday, underlining a tough task facing Japanese Prime Minister Shinzo Abe.

Valentina Matviyenko’s comment comes as Abe aims to make progress in a decades-old territorial row when Russian President Vladimir Putin visits Japan next month.

Japan claims a string of Russian-controlled western Pacific islands. The row over the island chain, seized by Soviet troops at the end of World War Two, has upset diplomatic relations ever since, precluding a peace treaty between the two countries.

“Russia’s sovereignty over the islands is certified by a certain international document. Russia cannot just give up that sovereignty,” Matviyenko told a news conference through a translator.

“There is no discussion going on at all on things like the handover of the islands.”

Abe met Putin in Russia’s eastern port city of Vladivostok in September and agreed to deepen economic ties and work for progress on talks to conclude a peace treaty.

Any Russo-Japanese joint economic activities on the islands, called the Northern Territories in Japan and Southern Kuriles in Russia, will need to stay within the framework of Russian law and sovereignty, said Matviyenko, a close ally of Putin.