Seven civilians have been killed and 12 injured in a suicide attack on a power plant in Samarra, north of the Iraqi capital of Baghdad.

The jihadist group Islamic State in Iraq and Syria (Isis) claimed responsibility for the attack, which occurred on the first day of Eid al-Adha.

Conflicting reports have emerged on the number of attackers involved in the power plant incident. There were three attackers according to an Iraqi security official, while the electricity ministry has cited four.

Iraq’s electricity ministry operates three power plants in Samarra’s Salahuddin province. It is unclear which one had been subject to the suicide attack. The ministry was unavailable for comments on Sunday.

The 20MW Samarra plant came online last year after three years of emergency shutdown following civil unrest in the country. The ministry also operates a 360MW diesel power plant in the province, which resumed operation in 2015. It had planned for a third 1,260MW facility in the province, but the scheme was put on hold because of security concerns.

Iraq has suffered chronic power outages for several years as a result of underinvestment in new infrastructure and damages to existing plants and networks during the US invasion in 2003. Despite the launch of an ambitious new generation programme in 2008, the sitution has worsened since 2014, when Isis established strongholds in Iraq. Several under-construction or planned power projects were delayed as a result of Isis taking over sites.

Shortage of power has become an increasingly important political issue in the country. In July, Iraqis took to the streets demanding an end to power cuts as temperatures in the country exceeded 50 degrees Celsius, forcing the government to declare mandatory holidays for government workers.

The attack on the Samarra power plant came at the end of a bloody week for Baghdad – a car bomb attack in the Sadr City neighbourhood of the city on 28 August killed 12 people and wounded 28.

According to the UN in Iraq, almost 125 civilians have been killed in the month of August alone, with another 188 injured across the country.