The two ships are believed to be Uruguayan naval frigates undergoing joint military exercises off Cape Town. The two Uruguayan frigates involved are the ROU Uruguay and the ROU Comandante Pedro Campbell, both formerly units of the Portuguese Navy.

The two frigates were only recently acquired, second-hand, from Portugal, and sailed straight to South Africa from the European country to participate in this year’s edition of the Atlasur series of naval exercises.

Atlasur is normally biennial, and involves South Africa, Argentina, Brazil, and Uruguay, with the function of host rotating between these countries.

The two ships were part of the Portuguese Comandante João Belo class, and each displaces 2 250 t, is armed with two by 100 mm and two by 40 mm guns and anti-submarine torpedo tubes, and has a top speed of 26 kts.

Although originally built in the late 1960s, they were significantly modernised in the 1990s, receiving new radar, sonar, electronic countermeasures and data-link systems.

According to unconfirmed reports, the Uruguayan frigates will be repaired at South Africa's naval dockyard in Simon's Town to enable them to continue to take part in the joint south-south naval exercise.

Once the exercise has been completed, further repairs will be undertaken in South Africa to allow the ships to return to Uruguay.

Ships have been damaged during exercises in the past, the HMS Leopard once being damaged by the SAS Pietermaritzburg.

- reporting by Keith Campbell and Martin Creamer