A Shell spokesman said its Nigerian subsidiary closed its Imo River field on August 28 after thieves caused spills that polluted farmlands and rivers.

Precious Okolobo said it would stay closed until they “leave the area for good.”

The field spreads across Rivers state and Abia state.

A special taskforce fights oil theft and militancy in Rivers, but does not operate in Abia.

A UN report released in early August said it will take as much as 30 years to clean parts of Nigeria’s oil-stained Niger Delta, a region of swamps, mangroves and creeks almost the size of South Carolina.

Nigeria is a top supplier of crude oil to the US.