The Niger delta avengers, which has been carrying out attacks on Nigerian oil facilities in the last few months, claimed responsibility on Sunday for five new attacks in the southern energy hub since Friday.
until today, the group had not laid claim to any attacks in the Niger delta -- the source of most of the OPEC member's oil -- since June 16.
Petroleum ministry sources said in late June that a month-long truce had been agreed with militants. But the avengers said they did not "remember" agreeing to a ceasefire.
Attacks in the Niger delta have pushed Nigerian crude production to 30-year lows, although the Nigerian national petroleum corporation (NNPC) said last week that output was rising due to repairs and a fall-off in attacks.
They added that on Saturday night they blew up two lines close to batan flow station in delta state run by NPDC, a subsidiary of NNPC.
The militants also said two chevron facilities close to abiteye flow station, in delta state, came under attack in the early hours of Sunday.