Armed pirates who stormed an oil service ship in southern Nigeria have kidnapped six foreigners and demanded a $1.3 million ransom for their release, police told AFP Wednesday.
"Three of those abducted are from Ukraine, two from India, one from Russia," Bayelsa state police spokesman Fidelis Odunna said of the Sunday attack.
"One of the kidnappers called to demand the sum of 200 million naira" (one million euros, $1.3 million), he added.
The kidnapping of foreign oil workers is common in Nigeria's oil-rich south, with the hostages often released following a ransom payment. It is however rare for police to discuss the details of ransom demands.
There has also been a recent series of kidnappings in northern Nigeria claimed by an extremist Islamist group, but those are considered a different phenomenon.
The Armada Tuah vessel operated by the Lagos-based Century Group with a crew of 15 was attacked by gunmen in waters off Bayelsa, according to police.
It was not immediately clear how far offshore the vessel was at the time of the attack.
"We have deployed intelligence personnel in search of the six workers," Odunna said.
The International Maritime Bureau which tracks sea attacks world-wide has described the waters off Nigeria as an emerging piracy hub, with many of the raids involving gunfire.
Militants in Nigeria's oil-producing Niger Delta region carried out scores of kidnappings before a 2009 amnesty deal led to a sharp decline in unrest, though incidents continue.
Five Indian crew members of an oil tanker who were kidnapped in December after heavily armed pirates stormed their vessel off Nigeria's coast were released last month.
Medallion Marine, a Mumbai-based shipping firm, said the hostages were freed in good health, but did not disclose whether a ransom had been paid, or whether Nigeria's security forces played any role in securing their release.
The theft of crude is considered a key motivation for pirates operating in the Niger Delta.
Armed gangs in the region have become notorious for blasting into pipelines and siphoning out crude for sale on the lucrative black market.
Oil Minister Diezani Alison-Madueke on Tuesday told an oil industry conference in Abuja that Nigeria was seeking international help to curb criminality in the region.
The head of Shell's Nigeria subsidiary, Mutiu Sunmonu, told the same conference that "there is still a lot more that must be done" to pacify the Niger Delta.
Meanwhile in a separate abduction case, a French family of seven kidnapped in northern Cameroon on Tuesday were believed to have been taken across the Nigerian border, Yaounde said, suggesting the hostage-takers may be linked to Nigeria's main Islamist insurgent group Boko Haram.
Nigeria is Africa's biggest oil producer and most populous country with an estimated 160 million people, where most in the north are Muslim while the south is predominantly Christian.