More Christians have been brutally murdered in Nigeria in the latest attack on Christian villages by the Islamist terror group Boko Haram.

At least two Christians died in the attacks on Kuburumbula and Boftari on Monday, according to International Christian Concern (ICC). One man was tied up with rope and "slaughtered" in front of his wife and children, witnesses said.

Kuburumbula lost the largest number, 47, of the 276 girls kidnaped by Boko Haram from their school in Chibok in April 2014.

The killings are just the latest in a recent series of attacks on Christians by Boko Haram which has distressed parents of the kidnapped girls by releasing a video saying they will only let them go if their own captured fighters are released. Eight Christians were reportedly shot dead by Boko Haram as they left a church service earlier this month.

In the first attack on Monday, insurgents burnt seven houses, vandalised shops and set alight market products, Pastor Filibus of the Christian Association of Nigeria told ICC, which is organising an "International Day of Prayer" for the persecuted church worldwide in November. 

In the second village, Mallum Tela Madu, a Christian, was dragged into the village, tied up with rope and then brutally murdered by the Boko Haram Islamists while his family were forced to watch. 

ICC reports that it is a new strategy by Boko Haram to deliberately target Christian villages in Nigeria.

"As the attacks increase in intensity and frequency, other villages are growing more terrified," says ICC.

The charity's regional manger William Stark said: "For the second week in a row, we are mourning the loss of Christians in Nigeria who were murdered by Boko Haram militants. This string of attacks has us deeply concerned for the safety of our Christian brothers and sisters in the Chibok area of Nigeria's northeast."