The defence minister “must explain to South Africans what a sanctioned Russian ship is doing at the Simon’s Town naval base and why there is so much secrecy surrounding it”, he said in a statement.
“Evidence suggests that over the last two nights there was unusual activity in the harbour with on-board cranes offloading cargo from the Russian commercial vessel onto trucks,” he said.
“This behaviour has local residents worried because the vessel is under sanctions by the US and European Union after Russia invaded Ukraine.”
The South African defence ministry has not commented on the ship’s visit.
The Lady R is a relatively small 7260-ton ship designed to carry vehicles and cargo containers. It is owned and operated by Transmorflot LLC, a Russian company registered in Dagestan.
The Telegraph approached Transmorflot LLC for comment.
The United States sanctioned Transmorflot and six of its vessels including the Lady R in May, saying they had been used to transport weapons for the Russian government.
Vessel tracking services show she switched off her transponder earlier this week. Her last known position was near Cape Town.
There is no evidence that South Africa has sold arms to Russia since the invasion of Ukraine began on February 24.
The National Conventional Arms Control Committee (NCACC), the government agency that all South African arms firms must apply for permission before exporting weapons, says it has no record of sales to Russia.
Modise visited Moscow in August to attend a conference hosted by Sergei Shoigu, Russia’s defence minister.
The same month she declined to say whether Armscor, South Africa’s state-owned defence company, was selling munitions to Russia.
In response to a written parliamentary question from opposition leader John Steenhuisen, she said she could not divulge details of specific arms deals because “unauthorised disclosure may cause serious implications to national security”.
