Militants and residents say an attack on Chevron's Escravos terminal has shut down the U.S.-based oil major's onshore operations in Nigeria.

Thursday's attack was the third assault on a Chevron Nigeria facility this month. It's the latest in a string of attacks claimed by the Niger Delta Avengers that has brought Nigerian production to a 20-year low.

Residents say a bomb on an underground pipeline feeding electricity forced Chevron to suspend operations at the terminal exporting more than 160,000 barrels a day.

The Avengers have ordered oil companies to leave the southern delta by the end of May. They say they want a greater share of Nigeria's oil wealth though there are reports they could be funded by Christian southerners opposed to President Muhammadu Buhari, a Muslim from the north.