The US envoy to South Africa has accused the country of supplying weapons to Russia despite its professed neutrality in the war in Ukraine.
Ambassador Reuben Brigety told local media he was “confident” that a Russian ship was loaded with ammunition and weapons in Cape Town last December.
South Africa’s President Cyril Ramaphosa said his government was looking into the claims.
The country has maintained claims of neutrality in the invasion of Ukraine.
Mr Brigety said at a media briefing in Pretoria on Thursday that Washington had concerns about the country’s stated non-aligned stance on the conflict.
He referred to the docking of a cargo ship in the Simon’s Town naval base between 6 and 8 December last year which he was “confident” uploaded weapons and ammunition “as it made its way back to Russia”.
“The arming of the Russians is extremely serious, and we do not consider this issue to be resolved,” he said.
He added that the US also had concerns about South Africa’s participation in military exercises with Russia and China during the anniversary of the invasion of Ukraine.
The naval exercises took place over 10 days in February and were criticised by opposition figures as an endorsement of the Russian invasion.
The South African authorities denied the war games were provocatively timed to coincide with the one-year anniversary and said the country routinely hosts similar drills with other nations, including France and the US.
South Africa previously abstained from a UN vote condemning the invasion. It also refused to join the US and Europe in imposing sanctions on Russia.
In response to a question raised by the leader of the opposition John Steenhuisen, Mr Ramaphosa told parliament on Thursday that the comments made by the US ambassador would be looked into.
The president asked opposition parties to allow for the process to be completed.
The US State Department has not yet commented on the claims.
