Islamic extremist group Boko Haram has attacked at least five churches Borno State, northern Nigeria, Christian Solidarity Worldwide (CSW) reports.

Gunmen reportedly used IEDs and petrol bombs to destroy churches in the Hawal Local Government Area, which is home to a predominantly Christian community, on the evening of July 30.

No one is thought to have died in the attacks, but two people were murdered in the Shaffa District of Hawul on July 26 by Boko Haram militants. Eyewitnesses say the victims were each beheaded, and their severed heads placed on their chests.

Boko Haram is an Islamist terror group, intent on "cleansing" Nigeria of Christians. Members have also attacked moderate Muslim communities.

At least 13 died and several more were injured in two mosque suicide bombings in Yobe state on July 29.

The first was detonated at an Izala centre as local Muslims met to pray, while the second took place at a mosque attacked to the family home of Potiskum's chief Imam.

A Muslim cleric was also abducted by Boko Haram militants along with his wife and two other people in the town of Katarko in Yobe state on July 28.

CSW Chief Executive Mervyn Thomas has denounced Boko Haram's "relentless campaign of religious cleansing" following the attacks.

"Boko Haram continues to commit war crimes by wilfully destroying churches...Moreover, the sect has illustrated once again its disregard for every religion and for the sanctity of human life, not only by targeting the innocent as they pray, but also by indoctrinating vulnerable girls for use as disposable commodities to fulfil its murderous purposes," Thomas said in a statement.

"Nigerians must put aside all religious, political and other divisions and unite in the national interest to overcome this destructive terrorist sect as a matter of urgency."

Boko Haram – whose name translates as 'Western education is forbidden' – is responsible for over 2,000 deaths this year alone. Led by Abubakar Sheka, the group plans to eradicate Nigerian democracy and replace it with an Islamic state guided by Sharia law.