North Korean leader Kim Jong-un, center, shakes hands with Russian President Vladimir Putin, second from right, at Amur Oblast in the Russian Far East in this photo released by the North's Korean Central News Agency, Sept. 14, 2023. Yonhap

North Korean leader Kim Jong-un has voiced hope for continuing to develop "meaningful and close" ties with Russian President Vladimir Putin, state media reported Wednesday, amid growing speculation that the Russian leader could soon travel to Pyongyang.

In a congratulatory message to Putin on the occasion of Russia's national day, Kim said the two nations' ties have evolved into an "unbreakable relationship of comrades-in-arms" following his summit with Putin in Russia's Far East in September last year, according to the Korean Central News Agency.

"The meaningful ties and close comradely relations, to be continued between us in the future, will further consolidate the eternal milestone of the DPRK-Russia relations in the new era," Kim said, using the acronym of North Korea's official name, the Democratic People's Republic of Korea.

Putin is expected to make a trip to North Korea as early as this month before paying a visit to Vietnam, the Russian daily Vedomosti reported earlier this week. The Kremlin earlier said Putin had accepted Kim's invitation to visit North Korea during last year's summit.

Japanese broadcaster NHK reported Wednesday that Russia is arranging Putin's visit to North Korea and that he could go "as early as next week" as part of a tour that would include a stop in Vietnam.

If realized, it would be Putin's first trip to Pyongyang since 2000, when Kim Jong-il, the late father of Kim Jong-un, ruled the country.

Signs were detected of the installing of a large-sized structure at Kim Il Sung Square in Pyongyang, the Voice of America, a U.S. news outlet, reported, citing satellite imagery. The move warrants attention for possible signs of North Korea's preparations for Putin's visit, it added.

North Korea and Russia have been bolstering military ties and expanding the scope of cooperation in various fields since the Kim-Putin summit.

Pyongyang is suspected of having provided weapons and munitions for use in Russia's war with Ukraine in exchange for Moscow's potential transfer of weapons technology and food aid. (Yonhap)