US research group 38 North says a train traveled from North Korea to Russia amid an allegation that Pyongyang is exporting weapons to Moscow.

The group released satellite imagery on Friday and said a three-car train had crossed a bridge between the two countries' borders.

The group said the purpose of the operation and the cargo the train was carrying could not be determined from the imagery.

38 North cited White House National Security spokesperson John Kirby's comment on Wednesday that the US believes that North Korea is covertly supplying Russia with a significant number of artillery shells.

In September, Pyongyang said it had never supplied weapons to Russia and had no plans to do so.

Freight train services between North Korea and Russia stopped in 2020 due to the coronavirus pandemic, but Russian media reported on Wednesday that the operations had resumed.

A Russian state-run news agency on Friday quoted the country's Embassy in Pyongyang as saying that Russia is very interested in importing clothing and shoes from North Korea.

The news agency said the two countries actively cooperated in this area in the 1980s and 1990s, but did not say why Moscow wants to resume imports. The agency also quoted the embassy as saying that the country has needs.

Russia may be trying to import clothing and shoes for military personnel deployed in Ukraine, as there are reports of heavy losses of military goods.