A group that claimed responsibility for a major attack on a pipeline in Nigeria’s oil-producing Delta region said it will carry out more strikes, just days after President Muhammadu Buhari vowed to crack down on “vandals and saboteurs”.

The Niger Delta Avengers has said it carried out the attack on a Shell underwater pipeline in February which interrupted oil flows and forced the company to shut down its 250,000 barrel-a-day Forcados export terminal for weeks.

Pipeline attacks and violence have risen in the southern swampland of Africa’s biggest oil exporter since authorities issued an arrest warrant in January for a former militant leader on corruption charges.

Last week Buhari, a former military ruler, said the government would crack down on pipeline saboteurs. And on Sunday the vice president’s office issued a statement that said a permanent pipeline security force was being considered.

“We are not deterred by such threats as we are highly spirited and shall continue blowing up pipelines until the Niger Delta people are no longer marginalised by the Nigerian actors,” said the Niger Delta Avengers in a statement.

The Delta’s oil provides 70 percent of state income in Africa’s biggest economy but, like much of Nigeria, the region has seen little development which has prompted militants to demand a greater share of crude revenues.

Niger Delta Avengers, unheard of before the Forcados attack, say they want to ensure that local people enjoy a quality of life which reflects the region’s contribution to the national purse.

The group said in its statement: “We take no pleasure in claiming innocent lives hence our struggle is geared toward attacking the oil installations in our region and not the people. And we shall stop at nothing until our goal is achieved.”

Buhari has extended a multi-million dollar amnesty signed with militants in 2009 but upset them by ending generous pipeline protection contracts.

Vice President Yemi Osinbajo visited the damaged Forcados terminal on Friday.

Sources have said repair work on the pipeline feeding Forcados crude oil to the export terminal is expected to take until June. But the vice president’s statement said repair work was expected to end in May. (Reuters)

•Photo shows Niger Delta militants.