The US ambassador to South Africa says the country has provided military supplies to Russia. The major African power has been viewed as taking a neutral position on the Russian invasion of Ukraine.

Ambassador Reuben Brigety told local media on Thursday that Washington is confident that weapons and ammunition were loaded onto a Russian cargo vessel at a naval base near Cape Town in December last year.

US State Department Principal Deputy Spokesperson Vedant Patel said, "The US has serious concerns about the docking of a sanctioned Russian cargo vessel. We have raised those concerns directly with multiple South African officials."

The South African presidential office said in a statement that "the ambassador's remarks undermine the spirit of cooperation and partnership" between the two countries.

The statement also said there is no evidence to support the allegations, adding that the government will launch an independent inquiry into the matter.

While maintaining its neutral stance on the Russian invasion, South Africa conducted a joint military exercise with Russia and China in February, drawing domestic criticism for showing a pro-Russia stance.