An internal customs service note dated September 21 declared "the suspension of the issuing of transit authorizations for oil products granted to users in Mali."
Authorizations that had already been given to supply oil products to Mali were also suspended.
Oil products intended for the U.N. MINUSMA peacekeeping force in Mali were exempted, the note added.
The move was made three days after the Malian junta's prime minister criticized against Niger's president during the U.N. General Assembly in New York.
Mali's Colonel Abdoulaye Maiga alleged that Mohamed Bazoum was not from Niger in a grievance-filled address.
A customs source, asking not to be named, said: "This measure is really motivated by security reasons, nothing else."
MINUSMA oil supplies would be "escorted to the Mali border," the source added.
The customs sources said the oil products come from Niger itself and from Nigeria, one of Africa's largest producers.
Several sources often report the hijacking of oil trucks on the Niger and Burkina Faso borders by jihadist groups.
Both Niger and Mali, where a junta seized power in 2020, have for years struggled to halt attacks by jihadists affiliated to al-Qaeda and the Islamic State group.
