Lagos - Nigerian oil militant group the Niger Delta Avengers on Sunday claimed five attacks on the country's oil and gas infrastructure in a revival of their sabotage campaign after a recent lull. Since early this year, the Avengers have been bombing pipelines as they fight to win the Niger delta region a bigger share of crude revenue and greater political autonomy. The sabotage is hitting the economy - the central bank governor has warned a recession is "imminent" - as the country is struggling with lower revenue as a result of the low global price of oil.In a series of statements posted on Twitter, the Avengers claimed that they bombed the state-owned Nigerian National Petroleum Corporation (NNPC) crude oil trunk line on Friday, and two Nigerian Petroleum Development Company trunk lines in Delta state. Avengers also said that on Sunday they bombed two Chevron oil wells in Delta state.According to a Nigerian state security officer, the Sunday morning explosions in Warri happened simultaneously."I just spoke with my men in the area and they confirmed the attack," the source said, speaking on condition of anonymity. "Preliminary investigations so far from our men in the field is that dynamite was used to blow up the facilities just like in previous attacks."Regional leader Eric Omare confirmed the Friday attack on the NNPC pipeline saying people living in the fishing villages dotting the winding mangrove creeks heard the attacks. "Yes, I got calls from locals in the area who heard the blast," Ijaw Youth Council spokesperson Omare said. The attacks break a relative lull in violence and show that the Avengers are still capable of strangling Nigeria's oil production. Last month, junior oil minister and NNPC head Emmanuel Kachikwu visited Niger delta communities and President Muhammadu Buhari met with a delegation of community leaders and promised to "rebuild" the region. But despite rumours of truce talks, the Avengers denied putting attacks on hold, saying their "high command never remembers having any agreement on ceasefire with the Nigeria government".The Avengers, who are believed to be highly skilled former rebels with insider knowledge of the region's oil and gas infrastructure, have warned against repairing the pipelines until their demands are met. "What is certain is that the Avengers are now being taken very seriously, as they have been credible in following through with their threats," Rhidoy Rashid, a London-based analyst at Energy Aspects, told AFP. "The attacks have been well-planned and cleverly executed, and have demonstrated a level of sophistication exceeding typical attacks on oil infrastructure in the Delta."