Piracy affects a number of countries in West Africa and has become an issue of global concern.
Pirates have attacked a Portugal-flagged container ship off the coast of Benin and kidnapped eight crew members, including three Russians, one Ukrainian, and the Bulgarian captain.
Shipping firm Transeste said pirates boarded the Tommi Ritscher vessel on April 19 off the coast of the West African country.
Eleven crew members were able to hide in the ship’s citadel and were later freed in a joint Benin Navy and Nigerian Special Forces operation.
"Regrettably, eight crew members remain missing and are now believed to have been kidnapped by the pirates," the Hamburg-based firm said on April 21.
The Russian Embassy in Benin and Togo confirmed that three Russian citizens were among the hostages.
Bulgaria's Foreign Ministry said the pirates also captured the Bulgarian captain of the ship. Ukraine said one of its citizens was kidnapped.
The Gulf of Guinea is a center of global pirate attacks, looting, and kidnapping for ransom.
Based on reporting by AFP, TASS, and Reuters
Sailor kidnappings surge 50% off West Africa
Number of crew kidnappings jumped from 78 in 2018 to 121 last year, according to International Maritime Bureau report.
The number of sailors kidnapped off West Africa surged by more than 50 percent last year, a maritime watchdog said on Tuesday, urging greater international cooperation to reduce piracy.
The abductions took place in the Gulf of Guinea, waters stretching thousands of kilometers (miles) from Angola in the south to Senegal in the north, which are considered among the world's most dangerous for attacks.
The number of crew snatched there jumped from 78 in 2018 to 121 last year - amounting to more than 90 percent of kidnappings reported at sea worldwide, the International Maritime Bureau (IMB) said in its annual piracy report.
"This region has recorded an unprecedented rise in crew kidnaps," said Michael Howlett, director of the Kuala Lumpur-based IMB.
He called for "increased information exchange and coordination between vessels, reporting and response agencies in the Gulf of Guinea".
Overall, however, reported incidents of piracy and armed robbery against ships worldwide fell in 2019 to 162 from 201 a year earlier, the watchdog said.
The Gulf of Guinea has now eclipsed the Gulf of Aden, off Somalia, as Africa's piracy hotspot, and countries in the region have been trying for years to bolster means of intervention and to increase cooperation.
Attacks in the gulf, home to Sub-Saharan Africa's two main oil producers Nigeria and Angola, have seriously disrupted international shipping routes and inflicted huge economic costs.
In 2017, the cost to West Africa was estimated at more than $818m, including naval activities and contracting security services, according to a report from Oceans Beyond Piracy, a programme that studied maritime attacks.
Criminal gangs in the past used to steal oil cargo, but have switched tactics over the past decade to kidnapping sailors for ransom as crude prices have fallen.
Much of the problem originates in the Niger Delta, in Nigeria, a base for pirates who use high-powered speedboats to raid passing ships and kidnap crews.
The Singapore Strait, the gateway for shipping to the trading hub, also experienced a jump in piracy with 12 armed robberies from vessels reported in 2019, the watchdog said.
But it added the incidents were "low-level" and usually limited to robbery.