South African authorities suspect the 22-year-old, 6,492 teu MSC Apollo containership was responsible for an oil spill at Algoa Bay on Saturday afternoon.
Bad weather in the intervening days has made investigations and clean-up operations difficult with the South African Maritime Safety Authority (SAMSA) unable to specify the scale of the spill.
Efforts are underway to protect the wildlife on the nearby islands of St Croix and Bird Island.
Algoa Bay is located the Eastern Cape on the east coast, 683 km east of the Cape of Good Hope.
SAMSA is having one of its busiest years thanks to the enormous switch in trading patterns with a significant swathe of the global merchant fleet avoiding the war-torn Red Sea on trips between Asia and Europe and instead heading around the coast of South Africa.
Late last month, another ship belonging to Mediterranean Shipping Co (MSC), the 6,966 teu MSC Antonia, lost 46 boxes overboard during severe weather conditions with another 305 containers damaged.