Seoul, Jun 28 (IANS): Senior diplomats of South Korea and Japan on Friday reaffirmed their commitment to closely working together to deter North Korean threats amid the growing military cooperation between Russia and the North, Seoul's foreign ministry said.

First Vice Foreign Minister Kim Hong-kyun and Japanese Vice Foreign Minister Masataka Okano reached an understanding during a bilateral strategic diplomatic dialogue in Tokyo, the ministry said.

They voiced "grave concerns" over Moscow and Pyongyang pledging mutual military assistance in a new treaty signed between their leaders at talks in Pyongyang last week, reports Yonhap news agency.

"The two ministers shared the need for close coordination between South Korea and Japan, as well as trilaterally with the United States and together with the international community, to work to deter North Korean threats amid the serious security situation posed by the North's deepening military cooperation with Russia," the ministry said.

They also discussed bilateral issues, including Japan's push to inscribe its Sado gold and silver mine complex on the UNESCO World Heritage list.

South Korea has expressed concern over Tokyo's reluctance to reveal the mine's history as once being the site where thousands of Koreans were forcibly mobilised to toil during World War II and called for Japan to reflect the "full history" of the mine.

"The ministers agreed to make efforts to continue the momentum for the development of their bilateral relations," the ministry said in relation to the Sado mine, without elaborating.

The ministers also discussed efforts to further improve ties, as next year will mark the 60th anniversary of the normalisation of bilateral relations.

Following the talks, Kim paid a courtesy call to Japanese Foreign Minister Yoko Kamikawa.