DAR ES SALAAM, Tanzania (AP) — Tanzania is denying allegations that some North Korean ships have been flying Tanzania's flag in violation of international sanctions.

Abdullah Hussein, the director-general of the Zanzibar Maritime Authority, on Wednesday called the allegations "void" and said Tanzania abides by U.N. resolutions targeting North Korea with sanctions.

NK News, a research and analysis group, reported on its website this month that nearly 50 vessels owned by or linked to North Korea have changed their flag to the Tanzanian one since March.

The ships are thought to be registered by the Tanzania Zanzibar International Register of Shipping under the Zanzibar Maritime Authority.

Hussein says Tanzania has been taking action. That includes deregistering all vessels deemed to be contravening international sanctions after allegations in 2013 that some Iranian ships carried the Tanzanian flag.