Paris-based FATF said the two countries were added to its list following a review.
Being added to the grey list is a reputational knock for the South African government, which has been trying to address shortcomings identified by the FATF.
Analysts say it could also mean South African clients at international financial institutions will be subject to enhanced due diligence checks. It could also complicate South African attempts to access funding and support from multilateral development institutions and official lenders.
The FATF is an inter-governmental organization that underpins the fight against money laundering and terrorism financing by setting global standards and checking if countries respect them.
Along with its alert on South Africa and Nigeria, the Financial Action Task Force said on Friday that it has suspended Russia's membership.
"The Russian Federation's actions unacceptably run counter to the FATF core principles aiming to promote security, safety, and the integrity of the global financial system," it said.
