Morocco and Nigeria join Bahrain, Belarus, Ethiopia, Kenya and Ukraine as having category A status. Russia has been banned over doping since November 2015.
The AIU, the independent anti-doping watchdog for track and field, said that in 2019, the Nigerian athletics federation failed to report on compliance as a category B country.
"This very serious situation motivated the AIU board to move Nigeria into category A," it said.
Turning to Morocco, the AIU said that, despite significant efforts, "a number of national level issues have not been addressed".
"The doping threat in Morocco remains acute and the AIU considers that more needs to be done to address the threat, where applicable, with the support of the relevant Moroccan authorities."