"The six members of the vessel's crew, who were taken hostage on July 4 and have spent the past 18 days in captivity in the Niger Delta, were released and are now safe," EMS Ship Management, the managers of the Singapore-flagged 'Siehem Peace', said in a statement posted on its website.
The militant group, the Movement for the Emancipation of the Niger Delta, has also said the hostages -- three Russians, two Filipinos and an Indian -- have been freed.
"This is a dividend of the current ceasefire and we hope that the federal government will begin to reciprocate our gesture by withdrawing the JTF (the Joint Task Force)," the group's spokesman Jomo Gbomo was quoted by media reports as saying in a statement.
The managers of the ship said the "happy news has been conveyed to the families of the seafarers. The seafarers who were released today will proceed to Lagos where they will receive full medical checks before flying back to their respective countries and homes."
The MEND has launched several attacks on international oil facilities in south Nigeria as part of its campaign to get what it calls a fairer distribution of the region's oil wealth to locals.
Last month, Nigerian President Umaru Yar' Adua offered an amnesty for those militants who lay down their arms by October 4 this year.
