The SA Agulhas II icebreaking polar supply vessel was meant to have left Cape Town last month to relieve a team based there since April 2025, the environment ministry said.

But it only received a shipment of specialised polar diesel required for Antarctic and sub-Antarctic operations on May 1, a statement read.

"The delay is primarily due to the global scarcity of fuel products linked to ongoing geopolitical developments in the Middle East," it added.

With the ship expected to depart in the coming days, there is "currently no immediate risk to the Marion Island over-wintering team", the ministry said.

The base on the island, about 1,920 kilometres (1,190 miles) southeast of Cape Town, had enough polar diesel reserves until about May 20 and food supplies for about two months.

There were also back-up petrol generators and nine stocked research huts across the island to support emergency requirements if necessary, the ministry said.

The newly arrived fuel shipment was undergoing testing and mixing in a process that ensures it does not crystallise or freeze in extremely cold weather.

Within two days of this being completed, it would be delivered to the SA Agulhas II, which would depart immediately on being refuelled, the ministry said.

The journey takes about five days.

The uninhabited and rocky Marion Island -- about 290 square kilometres (112 square miles) in size -- is a base for environmental and meteorological research.

The team dropped off there in April 2025 consists of 20 people, including technicians, meteorologists, birders, sealers and a killer whale specialist, according to the mission.