Pirates, probably Somalis, who seized a German freighter abandoned the vessel without any ransom after the crew went into hiding, the shipping company said on Monday.
The pirates had vanished by the time the British frigate Montrose arrived after steaming 15 hours over the Indian Ocean to the aid of the break-bulk carrier Beluga Fortune. All the crew of 16 were safe, the Bremen-based Beluga shipping company told a newspaper, the Weser Kurier.
German Foreign Minister Guido Westerwelle confirmed the ship was safe and voiced relief.
German shipping companies have developed a standard procedure of shutting down all power and hiding the crew when a ship is attacked. The same defence tactics foiled an attack on a Hamburg-owned ship several weeks ago.
British Navy sailors boarded the Beluga Fortune at noon Monday, 1,200 nautical miles east of Mombassa, after the Montrose came alongside, the newspaper said in a release to other media.
The Beluga Fortune was one of two vessels attacked by pirates at the weekend. The other was an unladen Singaporean liquid-gas carrier, the York.
"Our precautions and concentrated training of the crew worked out very well," said a relieved Niels Stolberg, chief executive of Beluga Shipping, a company which works with specialized cargoes.
After repairs of minor damage, the ship was resuming its voyage to Richards Bay in South Africa.
The crew had radioed at 7 a.m. Sunday that pirates were attempting to board, and immediately stopped the engine, blocked the fuel lines and switched off all systems on the bridge.
That meant the pirates could not themselves get the hijacked ship to move, nor could they force the crew at gunpoint to help.
The ship has a concealed strongroom with seven days of food and radio communications gear and the pirates could not find it.
A reconnaissance plane with the European Union naval force Atalanta reached the scene at noon Sunday and observed the freighter drifting. Later the naval boarding party searched all decks before telling the crew to come out their hiding place.
Westerwelle said: "We have the vigorous intervention of British naval forces to thank." He said the recovery of the Beluga Fortune was a fine example of international cooperation against piracy.
Beluga said it was unclear where the pirates went, but the crew, two of whom are German nationals, suspected that another freighter lurking in the area was stolen and was being used as a pirate mother ship.
The site of the attack was four days' steaming from the African coast, much too far for a direct coast-based raid. The criminals use small speedboats to board merchant ships on the high seas.
Efforts were meanwhile continuing to recover the Greek-owned York which was seized Saturday off the coast of Kenya. It has a German captain and a crew of 16. The shipping company in Piraeus refused comment, with a staffer saying ransom negotiations are never public.
Interunity Management Corporation (IMC), which manages the York, said: "It is still moving towards Somalia.
Somali pirates are currently holding more than 20 vessels and about 400 mariners to ransom.
The International Maritime Bureau says 44 percent of the 289 pirate attacks recorded round the globe so far this year, or 126, have been by Somalis. The Somalis boarded 39 ships and managed to take 35 to their bases on the Somali coast.