By Paul Carsten and Alexis Akwagyiram
ABUJA (Reuters) - A militant group in Nigeria's oil-rich southern Niger Delta threatened on Thursday to cripple Africa's top oil producer and biggest economy 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 Atiku, a business and ex-vice president, in Saturday's election in Nigeria, Africa's biggest democracy.
The Niger Delta Avengers were behind a 2016 wave of violence that helped push Nigeria into recession. However, no substantial attacks have been carried out by any groups in the Delta region since January 2017.
The group, in a statement posted on its website, warned that if Buhari is re-elected there would be "a perpetual recession for Nigeria".
The president's spokesmen did not immediately respond to phone calls, emails and text messages seeking comment.
Attacks on pipelines and other facilities in the Niger Delta in 2016 cut Nigeria's crude output from a peak of 2.2 million barrels per day (mbpd) to near 1 mbpd - the lowest level seen in Africa's biggest economy in at least 30 years.
That, combined with low oil prices, pushed the OPEC member state into its first recession in a quarter of a century - crude sales make up two-thirds of government revenue and 90 percent of its foreign exchange.
Atiku, the candidate representing the main opposition People's Democratic Party, has proposed to devolve more power to regions in a policy dubbed "restructuring" that would give states greater control over their finances.
It would enable oil-rich states in the south to retain a greater share of the revenues generated for crude production.
"We are adopting Alhaji Atiku Abubakar, as the sole candidate to be voted for by all the people of the Niger Delta as a result of his political ideology which is in tandem with our agitation for equitable and fair principles of federalism," the group said.
The Avengers said that, if elected, Atiku should start a "restructuring of Nigeria" within six months to forestall further attacks in the Niger Delta.
"Atiku has said that restructuring will begin on the day he takes office, so he will keep his word," Paul Ibe, a spokesman for the main opposition candidate, said in a telephone interview.
He said Atiku repeated his commitment to the policy in the last few days at a rally in the oil hub city of Port Harcourt.
Buhari's government held talks with the militants to address their grievances over poverty and oil pollution in the Delta for more than a year and this led the group to halt attacks.
Any resumption of attacks would renew pressure on Nigeria as it recovers from its worst recession in a generation. The country is also facing separatist movements in the southeast and Islamist militants in the northeast.
(Reporting by Paul Carsten and Alexis Akwagiram; Additional reporting by Felix Onuah; Writing by James Macharia and Alexis Akwagyiram; Editing by Mark Heinrich and Toby Chopra)