North Korean leader Kim Jong Un touted a newly built street of flats for families of soldiers killed supporting Russia's war against Ukraine, state media reported Monday, with photos showing him accompanied by his daughter.

North Korea has deployed thousands of troops to fight for Russia, according to South Korean and Western intelligence agencies, and Seoul has estimated that around 2,000 have been killed.

Analysts say North Korea is receiving financial aid, military technology and food and energy supplies from Russia in return.

"The new street has been built thanks to the ardent desire of our motherland that wishes that... its excellent sons, who defended the most sacred things by sacrificing their most valuable things, will live forever," Kim said in a speech released by the official Korean Central News Agency.

The report on Monday did not mention Russia, but Kim last week pledged to "unconditionally support" all of Russian President Vladimir Putin's policies and decisions.

"Before their death, the heroic martyrs must have pictured in their mind's eye their dear families living in the ever-prospering country," he added.

Photos released by KCNA show Kim touring the new homes built for the families on Saeppyol Street, alongside his teenage daughter Ju Ae, widely viewed as his heir apparent.

Seoul's spy agency said last week she had now been clearly "designated as a successor", citing her participation in high-profile events with her father.

One photo shows Kim speaking with what appeared to be the family members of a fallen soldier on a sofa, his daughter standing behind them.

Other photos show families checking the utilities in their new flats.

The rollout comes ahead of Pyongyang's biggest political event on the calendar -- the party congress -- scheduled to take place later this month, although the exact date has not been announced.

Attention is on which foreign and domestic policy directions Kim will declare to set the country's course, as well as whether Ju Ae will be given any official party titles.

The timing of the street inauguration is a "highly calculated political move to justify its soldier deployment" ahead of the party congress, Hong Min, an analyst at the Korea Institute for National Unification, told AFP.

"It visualises the state providing concrete compensation to the families of fallen soldiers... as a symbolic showcase," he said.