ABUJA: Attacks on pipelines in Nigeria over the weekend have since then cost Africa’s biggest economy around 470 million naira ($2.4 million) per day in lost gas and electricity, the government said on Thursday.

The sabotage in the southern oil-producing Niger Delta, for which the former militant group in the region denied responsibility, followed years of relative calm in that part of Africa’s biggest crude producer.

A spate of attacks there on oil installations and kidnappings of expatriate workers were halted by a 2009 amnesty.

State oil company NNPC said on Wednesday it had closed two of its four refineries due to subsequent crude supply problems.

No one has claimed responsibility for the attacks, in which former members of the largely defunct Movement for the Emancipation of the Niger Delta (MEND) denied involvement.

“What happened was not carried out by ex-militants,” former MEND commander “Ex-General Pastor” Reuben Wilson told journalists in the southern city of Yenagoa on Thursday.

Last week authorities issued an arrest warrant for MEND commander turned businessman Government Ekpemupolo, known as Tompolo, as part of a crackdown on corruption.