N.Korea's Kim to visit Russia in spring or summer

The exact date of the trip has not been set yet, Bashkin said.

The United States last week imposed new sanctions on North Korea over its nuclear weapons programme, the first such steps since a U.S.-North Korean summit collapsed last month.

The Kremlin confirmed on a conference call that a trip by Kim to Russia was being worked on but said that it was not able to provide further details.

"As soon as there is a concrete agreement on time, place and the form of the meeting, we will present the relevant information," Kremlin spokesman Dmitry Peskov told reporters on a conference call.