The attacks are the latest in a Delta region situation that a major local youth group said is "rapidly deteriorating and getting out of control", putting intense pressure on Nigeria's stretched finances.
Early on Friday, the group said via its Twitter account it had blown up a pipeline in Nigeria's Bayelsa state owned by Italy's ENI, hours after attacks on another ENI pipeline as well as one belonging to Shell Petroleum Development Company of Nigeria Ltd (SPDC).
"At about 3:30am our (@NDAvengers) strike team blew up the Brass to Tebidaba Crude oil line in Bayelsa," the group said on a Twitter feed it uses to claim attacks.
The Avengers say oil firms in the Delta are responsible for pollution and say the poor swampland region fails to reap any benefit from the wealth on which it sits.
In a statement it said its attacks had brought Nigeria's oil production to just 800,000 barrels per day (bpd), from 2 million bpd, "without killing a soul", though they hit infrastructure feeding crude grades already under force majeure.
The ENI pipeline is used to transport Brass River crude.
On Friday afternoon, the Avengers warned ENI directly not to start repairs or "we will make you regrets it".
Shell's Forcados crude oil, where another pipeline was attacked overnight, has been under force majeure since February. The group also hit ENI's Ogboinbiri-Tebidaba and Clough Creek-Tebidaba pipelines in Bayelsa.
Force Majeure is a term that suspends supply obligations to customers in the event of unforeseen circumstance.
ENI did not immediately respond to a request for comment. A spokesman for the SPDC, which operates the Forcados line, said the company was "investigating reports of an attack on its pipeline in the Western Niger Delta".
Ayiri Appah, a resident of Ogboinbiri, where the ENI pipelines are located, said he "heard a loud sound" from the area between 2 and 4 am local time, and said "some community boys who secure the pipelines also told me they heard the sound of dynamite explosions in those areas."
Three grades of Nigeria's oil - Forcados, Brass River and Bonny Light - are under force majeure, while ExxonMobil lifted force majeure on Qua Iboe, the country's largest export stream, on Friday.
Nigeria's oil minister said on Thursday that production was 1.6 million bpd. Even if the most recent attacks, which also included oil installations belonging to Chevron under its Escravos grade, took out all exports of the oil associated with them, June production would remain near 1.2 million bpd.
Experts said the violence showed little sign of abating, and would keep pressure on the Nigeria's oil production and finances. President Muhammadu Buhari, a Muslim from the north, on Thursday canceled what would have been his first visit to the Delta region since taking office.
The Avengers have accused Buhari of ignoring local problems by having never visited the Christian region in the south.
The Ijaw Youth Council, which represents one of the largest ethnic groups in the Delta, called on Buhari to "urgently and personally take charge ... to return peace and normalcy to the region."
Elizabeth Donnelly, assistant head of the Africa Programme with Chatham House, said the cancellation was a "missed opportunity" that could hamper efforts to engage with locals.