A militant group in Nigeria’s oil-rich southern Niger Delta threatened on Thursday to cripple Africa’s top oil producer if President Muhammadu Buhari is re-elected in a vote due to be held on Saturday.

The Niger Delta Avengers - who have been demanding a greater share of the oil revenue produced in the impoverished southern region - said in a statement they hoped to end Buhari’s rule through elections and that opposition candidate Atiku Abubakar was their preferred choice for president.

Buhari faces a tight contest against Abubakar, a business and ex-vice president, in Saturday’s elections in Nigeria, Africa’s biggest democracy.

Read more: Reuters