Russia says it has no information on North Korea’s claims that it has successfully conducted experimental uranium enrichment.

Russia’s Foreign Ministry said in a regular news briefing Friday that Moscow has not obtained any information on Pyongyang’s claims that it has enriched uranium and is weaponizing it.

Last Friday, the North’s state-run Korean Central News Agency quoted Pyongyang as saying in a letter sent to the U.N. Security Council that it successfully conducted experimental uranium enrichment and is in the process of building more nuclear weapons.

Also in the letter, the North said its reprocessing of spent fuel rods is in the final phase and extracted plutonium is being used to make weapons.