Russian President Dmitry Medvedev has ratified a civil nuclear energy pact with Japan.
The accord allows the transfer of Japanese technology to Russia and the sale of more Russian uranium to Japan.
The pact was passed by the lower and upper houses of the Russian parliament in December last year and was awaiting presidential ratification to go into effect.
Japan draws around a third of its total electrical power needs from its 54 nuclear reactors.
It is searching for new markets to export infrastructure technologies including power plants.