(CNN) China and Russia have sent home more than half of their North Korean workers, likely tens of thousands of people, according to reports submitted to the UN North Korean Security Council sanctions committee.

Russia's report said that the number of North Korean workers with valid work permits decreased from 30,023 to 11,490 persons.

In its report, China, the strongest ally of North Korea, said more of half of its income-earning North Korean nationals had been repatriated.

A UN diplomat confirmed to CNN that one-page reports from Beijing and Moscow were sent to the committee on sanctions, as required by a December 2017 Council resolution demanding repatriation of all North Korean workers by the end of this year.

Reuters first reported this story. CNN could not immediately confirm the figures given and China has previously been accused of trying to find ways around North Korea sanctions.