Russia and China have expressed serious concern about the tension on the Korean peninsula and urged North Korea to return to six-nation talks on its nuclear program.

Chinese President Hu Jintao and Russia's Dmitry Medvedev made the call for a resumption of the talks in a joint statement released at their meetings Wednesday in Moscow.

It said they "expressed serious concern in connection with the situation on the Korean peninsula."

It called for the swiftest possible return to the talks, which broke down months ago.

The statement included no new initiatives on the mounting problem and used language that appeared aimed at avoiding angering North Korea.