European Union naval forces have rescued 24 sailors from a Maltese-flagged oil tanker that was attacked by pirates off the coast of Somalia.

The Hellas Aphrodite, carrying petrol from India to South Africa, was seized on Thursday when armed pirates opened fire with machine guns and rocket-propelled grenades before boarding the vessel.

The crew locked themselves inside a fortified citadel while the attackers took control of the ship.

A Spanish warship, the ESPS Victoria, operating under the EU's anti-piracy mission Operation Atalanta, reached the tanker on Friday afternoon. Special forces boarded the vessel and found all 24 crew members unharmed.

"The crew is safe and no injuries have been reported. Throughout the incident, they remained in the citadel in direct contact with Atalanta," the EU mission said, adding that a "show of force" had prompted the pirates to abandon the ship before the warship arrived.

It added that the threat risk in the area "remains critical" as the pirates are still in the area.

The rescue operation involved a helicopter, drone and surveillance aircraft. Just hours earlier, another ship in the same area was approached by a small speedboat but managed to evade it.

It is the latest in a spate of attacks that have created concern about a resurgence of piracy in the area.

Such activity had declined when international naval patrols and security measures were introduced after peaking more than a decade ago.

However, attacks by Yemen's Houthi rebels on ships in the Red Sea, which have been carried out for the past two years, have led vessels to be diverted through East Africa's Indian Ocean - creating new opportunities for Somali gangs.

There were seven reported incidents of piracy that took place off the coast of Somalia last year, according to the International Maritime Bureau - including three hijackings. It reported only one incident of piracy in 2023.