The militant group Niger Delta Avengers (NDA) has issued a renewed threat to international oil companies as Nigerian President Muhammadu Buhari reportedly plans a visit to the troubled region, Newsweek reported.

The Avengers, which has carried out a series of attacks on oil pipelines and facilities in the Delta region, issued a statement warning companies —including Dutch giants Shell and U.S. firm Chevron—that “it’s going to be bloody this time around. Your facilities and personnel will bear the brunt of our fury, which shall fall upon you like a whirling wind,” said the statement, attributed to NDA spokesman, Mudoch Agbinibo.

Buhari will visit the Niger Delta region for the first time since taking office a year ago. In addition, he said that the government would hold talks with leaders in Nigeria’s main oil-producing region to address their grievances, in a bid to stop a surge in pipeline attacks.