The Hercules vessel, which was engaged in the work of oil platforms of Italy's Saipem, was attacked by the Nigerian militants on July 24. The gunmen later released the vessel along with seven crewmembers, and retained five men.
"According to our data, the attack was carried out by militants of the so-called Liberation Army. So far, they have made no demands and there is no information about the location of the hostages," the embassy said.
According to the embassy, there are also two Ukrainians and one Pole among the men seized by the militants.