MOSCOW - UN Secretary General Ban Ki-moon voiced concern on Sunday over North Korea's launch of short-range missiles, urging Pyonyang to refrain from further launches and return to stalled nuclear talks with world powers.Ban, who spoke to Russian state news agency RIA Novosti during a visit to Moscow, called North Korea's launch of three short-range missiles from its east coast on Saturday a "provocative action"."We are very worried over North Korea's provocative action," he told RIA in comments translated into Russian."I hope North Korea will refrain from further such actions," Ban said. "They must soon return to talks and lower tensions."The UN chief also called on Russia to exert its influence to help steer North Korea back to nuclear talks.Launches by the North of short-range missiles are not uncommon but, after warnings from the communist state of impending nuclear war, such actions raised concerns about regional security and prompted Western powers to urge restraint.Tension on the Korean peninsula has subsided in the past month, having run high for several weeks after Pyongyang's third nuclear test in February.