Russia says North Korea's leader has accepted an invitation to Moscow in May, South Korea's Yonhap reports.
The news agency cites a written response from the Kremlin, but says it does not mention Kim Jong-un by name.
Yonhap quotes a Unification Ministry official as saying the reference to the leader could be ambiguous, as Kim Yong-nam is the nominal head of state.
Kim Jong-un has not made any overseas visits since taking power in North Korea in late 2011.
His first destination will been keenly watched for what it might indicate about his policies and strategy.