In a press briefing at the embassy, Alexander Timonin confirmed Kim, who has yet to travel abroad since coming to power more than three years ago, was on course to attend Moscow's World War II anniversary celebration on May 9.
"We... Are expecting the visit by the top leader of the DPRK," he told reporters, using the North's official name.
"We are talking about Kim Jong-Un, the North's top leader," he clarified.
The North's state-run media has given no indication who, if anyone, would attend.
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Kim Yong-Nam regularly travels overseas and represented North Korea at this week's Asia-Africa summit in Jakarta.
If Kim Jong-Un does go to Moscow, it would be his first foreign trip and open to minute scrutiny -- especially with other world leaders, including China's Xi Jinping, expected to be there.
"Apart from attending the main event, a bilateral meeting with President Putin could also take place," Timonin said.
Kim, believed to be in his early 30s, took power after the death of his father Kim Jong-Il, in December 2011.
The young leader has received a number of high-ranking Chinese officials in Pyongyang, but the most prominent foreigner he has met in the past three years is the former NBA basketball star Dennis Rodman.
Kim Jong-Il rarely travelled overseas as leader due to his rumoured fear of flying, limiting his foreign trips to China and Russia, which he could reach by train.
It would also signal Kim's desire to reduce his country's dependence on China, which remains North Korea's main ally, diplomatic protector and economic buttress.