Moscow was making every effort to free the six Russian sailors captured by pirates in Nigeria, the Russian Foreign Ministry said Wednesday. \"Russian Foreign Ministry and Russian Embassy to Nigeria, with a close contact with the ship owner and the Nigerian authorities, are taking all necessary measures for sooner release of the abducted seamen and to secure their safety,\" the ministry said in a statement on its website. On Monday, pirates kidnapped six Russian citizens and one Estonian national, leaving the other nine crew members onboard a ship which was servicing hydrocarbon extraction platforms in the shelf off the southern coast of Nigeria. The Bourbon Liberty 249, belonging to a French company, was used to tow anchors for oil rigs or mobile drilling rigs. The vessel\'s crew worked on maintenance of oil platforms off Nigeria\'s shores. Russian diplomats in Nigeria confirmed to Interfax news agency earlier Wednesday the abduction of six Russian citizens, adding their whereabouts were unknown. Kidnappings for ransom are widespread in that part of Nigeria, Africa\'s largest oil producer.