SEOUL, May 12 (Reuters) - Russia's President Vladimir Putin told his newly elected South Korean counterpart, Moon Jae-in, in a phone call on Friday that he is ready to play a "constructive role" in resolving North Korea's nuclear threat, the South's presidential office said. Putin made the comment after Moon said the foremost task to boost cooperation between the two countries was to strengthen strategic bilateral communication to find a solution to curb North Korea's nuclear threat, the Blue House said in a statement. "We hope for Russia to play a constructive role in order for North Korea to stop with its nuclear provocations and go the way of denuclearisation," Moon was citing as saying to Putin in the 20-minute conversation. "I, too, aim to find a way to begin talks quickly between North and South Korea as well as the six-party talks," Moon said, referring to talks aimed at denuclearising North Korea involving the United States, China, Japan, Russia and the two Koreas. The talks collapsed in 2008 after North Korea launched a rocket. Tension has been high for months on the Korean peninsula over North Korea's nuclear and missile development and fears it will conduct a sixth nuclear test or test another ballistic missile in defiance of U.N. Security Council resolutions. Moon is a liberal who advocates a more conciliatory approach to North Korea compared with his conservative predecessor. Moon also expressed hopes the two countries would be able to cooperate in developing East Asia, including extending a natural gas pipeline from Siberia to South Korea, the Blue House said. Putin said he was ready to help in all of the matters they discussed and the two leaders invited each other for state visits, the Blue House added. Moon said he would send a special envoy to Russia soon and Putin said he would welcome the envoy. The two leaders said they looked forward to meeting at the Group of 20 summit meeting in Germany in July. Earlier in the day, Moon spoke with British Prime Minister Theresa May and German Chancellor Angela Merkel, the Blue House said. He asked them to help in curbing North Korea's nuclear programme and both promised to.