According to Reuters' Jessica Donati, West African pirates have freed a gasoline tanker they hijacked last week, after stealing some of the cargo, the ship owner said on Friday, in a fresh example of a growing trend in the region to hold vessels briefly to offload valuable oil products.

Nick Fell, a spokesman for BW Maritime, said the company thought the tanker BW Rhine had been taken for the gasoline it was carrying, which was worth millions of dollars.

“We believe that was the purpose. Some of the cargo has been stolen,” Fell told Reuters.

All 24 crew members were heading for safety, Fell said.

The hijacking appears typical of a pattern developing off West Africa. At least 16 such incidents have been reported along the coastline from Togo to Nigeria, according to the International Maritime Bureau (IMB) Piracy Reporting Centre.

“The duration tends to be 5-10 days, and the main reason is to steal the cargo,” said Cyrus Mody, a spokesman for the International Maritime Bureau.

Fell said the BW Rhine and its crew were headed for safety at a nearby port but declined to specify the location or say whether any of them had been harmed.

The BW Rhine was seized from anchorage off Lomé, Togo on April 28, the first incident of its kind near the country’s capital, BW Maritime said.

Three of the crew members, as well as the captain, were Indian, while rest of the crew were Filipino or Chinese, including some from Hong Kong.

Mody at the IMB said the ferocity of the attacks on the tankers varied widely from case to case, but in general, West African pirates were more violent than those off East Africa.

He added that most cases off the West African coast were unreported, either for fear of triggering another attack or possibly for insurance reasons.

East African pirates, notably those based in Somalia, tend to hold vessels and crew for ransom.

In West African countries, especially Nigeria, there is a large and highly developed black market for oil and its products.

(Reporting by Jessica Donati, Emma Farge and Sarah McFarlane; Editing by Anthony Barker)