Russian President Vladimir Putin has offered condolences to North Korean counterpart Kim Jong Un over devastating floods that caused untold casualties and damaged thousands of homes, the Kremlin said on Saturday.

The North, in turn, said Sunday that Putin had also offered "immediate humanitarian support" to aid its recovery efforts, to which Kim responded that he "could deeply feel the special emotion towards a genuine friend".

Pyongyang said this week it had seen a record downpour on July 27 which killed an unspecified number of people, flooded dwellings and submerged swathes of farmland in the north near China.

"I ask you to convey words of sympathy and support to all those who lost their loved ones as a result of the storm," Putin said in a telegram to Kim.

"You can always count on our help and support."

"The message of sympathy from Moscow was conveyed to the Foreign Ministry of the DPRK" on Saturday, said the official KCNA, noting it was immediately reported to leader Kim.

Kim thanked Putin for the outreach but said "already-established plans as state measures were taken at the present stage".

Regarding the offer Kim said "if aid is necessary in the course, he would ask for it from the truest friends in Moscow", KCNA reported.

Pyongyang said on Wednesday that officials who neglected their disaster prevention duties had caused unspecified casualties, without providing details on the location.

It said on Saturday that there were no casualties at all in the Sinuiju area, the region Pyongyang claimed suffered the "greatest flood damage."

North Korea and Russia have been allies since the North's founding after World War II and have drawn even closer since Moscow's 2022 invasion of Ukraine.

Media in South Korea, which has offered urgent support to the victims, said this week the toll of dead and missing could be as high as 1,500.

Kim lashed out at the reports, dismissing them as a "smear campaign to bring disgrace upon us and tarnish" the North's image.

North Korea is accused of breaching arms control measures by supplying weapons to Russia for use in its war in Ukraine.

Natural disasters tend to have a greater impact on the isolated and impoverished country due to its weak infrastructure, while deforestation has left it vulnerable to flooding.