The six men, working for the US oil company Chevron, were kidnapped by the separatist Movement for the Emancipation of the Niger Delta (MEND).
After the abduction, MEND spokesman Jomo Gbomo sent foreign news agencies a list with the names of the kidnapped workers, saying that all the hostages would be unconditionally released on May 30 provided that foreign companies did not try to secure their release by offering ransom.
Gbomo explained that the purpose of the abduction was to warn the Anglo-Dutch oil giant Shell against returning to some oil fields in the Nigerian federal states of Bayelsa and Delta.