North and South Korea are on the brink of war, a top Russian diplomat has warned, calling for both countries to exercise restraint and sit down for talks. In Moscow's bleakest assessment of the situation on the Korean peninsula yet, Russian deputy foreign minister Alexei Borodavkin said tensions between the two countries were running at their highest and most dangerous level in a decade. "Tensions on the Korean Peninsula could not be any higher. The only next step is a conflict," he told foreign policy experts at a round table on the subject in Moscow. His prediction came two months after North Korea vowed to wage "a sacred war" against South Korea and its biggest backer, the United States. Tensions bubbled over in March after Washington and Seoul concluded that a North Korean submarine had sunk a South Korean naval vessel in the Yellow Sea. Mr Borodavkin called for the investigation into exactly who was responsible for the sinking of the vessel, the Cheonan, to be urgently closed in order to remove an obvious source of tension. Describing the standoff between the two Koreas as a "hangover from the Cold War," Mr Borodavkin said Russia, which is one of the six countries involved in talks with North Korea over its nuclear programme, was doing all it could to try to prevent an outbreak of hostilities. But he said responsibility for keeping peace in the volatile region was shared equally between North and South Korea. He condemned North Korea's nuclear testing programme but also criticised the way the United States and South Korea had increased their military manoeuvres in the wake of the sinking of the Cheonan.