The U.N. secretariat in a statement voiced "grave concern" and said it "calls for the urgent release of the detained Ivorian soldiers."
"It strongly supports all efforts to facilitate this release as well as the restoration of confidence and promotion of good neighborliness between the two countries," it said.
Ivory Coast said that the soldiers were detained on July 10 at the Bamako airport as they flew in to provide backup to the U.N. peacekeeping force MINUSMA, one of the international body's largest and most dangerous missions.
The junta insists that they are mercenaries as the two-month standoff between the nations continues.
Guterres, in a recent interview with French broadcasts RFI and France 24, said it was "obvious" they were not mercenaries, prompting Mali's junta-appointed prime minister, Colonel Abdoulaye Maiga, to attack the U.N. chief in his speech to the General Assembly.
"Mr. Secretary-General, Mali shall exert all legal consequences over your actions," Maiga said in his Saturday address to the U.N.
Relations between Mali and Ivory Coast began to deteriorate after the military seized power in Mali in August 2020.