The Nigerian newspaper ThisDay published a statement Monday from the Movement for the Emancipation of the Niger Delta claiming responsibility for targeting regional pipelines.
"'Hurricane Exodus' continues to gather strength as it sweeps through the swamps and creeks in the Niger Delta," the statement read.
MEND said it was sorry for the environmental damage but considered it "a sacrifice for freedom we will all have to endure."
The militant group said its campaign was a response to rampant oil theft in the region. It said Nigerian security forces "aided and abetted" the theft.
Oil companies working in Nigeria blame militants for oil spills and theft.
Royal Dutch Shell last week resumed shipping oil from the region after a brief closure because of pipeline problems.
The government blamed instability in the Niger Delta for its failure to meet a 2013 production target of 2.53 million barrels of oil per day.
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