South African President Cyril Ramaphosa said on Sunday that an independent inquiry has found no evidence that a Russian ship had collected weapons from the country late last year destined for Russia.

In claims that sparked a diplomatic row, the US ambassador to South Africa, Reuben Brigety, told local journalists in a May briefing that Russian cargo ship Lady R had uploaded weapons at a naval base near Cape Town in December.

The US accusations raised questions over South Africa's professed stance of non-alignment and neutrality over Russia's war in Ukraine and concerns of possible Western sanctions.

In an address to the nation, Ramaphosa said the accusations had a damaging effect on South Africa's economy and its standing in the world.

"The panel found that there was no evidence to support the claim that the ship transported weapons from South Africa destined for Russia," Ramaphosa said.

"No permit was issued for the export of arms and no arms were exported."

Ramaphosa said the ship had docked at the base to deliver equipment that had been ordered for the South African National Defence Force in 2018 by South Africa's arms procurement company Armscor.

He said he could not reveal details of the equipment offloaded because that could compromise important military operations and put South African soldiers' lives at risk.

"When all matters are considered, none of the allegations made about the supply of weapons to Russia have been proven to be true," Ramaphosa said. "None of the persons who made these allegations could provide any evidence to support the claims that had been levelled against our country."

When the accusations were made, South African officials were quick to reject the claims, and Ramaphosa launched the independent inquiry led by a retired judge.