Islamic State West African Province (ISWAP) claim they killed the captives to avenge for the killing of their leaders Abu bakr al-Baghdadi and Abul-Hasan Al-Muhajir in and Syria.
A video released on Wednesday showed 13 hostages, 10 believed to be Christian and three Muslim. ISWAP claimed they spared the lives of two of the Muslims, reported.
The deaths came after an earlier video saw the hostages plead with the Christian Association of Nigeria (CAN) to negotiate their release.
In a statement, ISWAP said: 'We killed them as a revenge for the killings of our leaders, including Abu bakr al-Baghdadi and Abul-Hasan Al-Muhajir in Iraq and Syria.'
United Nation Secretary General Antonio Guterres offered his condolences, with his spoken Stephane Dujarric saying in a statement: 'The Secretary General is deeply concerned about reports that civilians have been executed, and others abducted, by armed group in northern Borno State, northeastern Nigeria.
'He expressed his deepest condolences to the families of the victims and reiterates the solidarity of the united Nations with the people and Government of Nigeria.'
Jihadis Boko Haram and its IS-affiliated Islamic State West Africa Province faction have recently stepped up attacks on military and civilian targets in Nigeria.
Boko Haram killed seven people on Christmas Eve in a raid on a Christian village near the town of Chibok in northeast Nigeria's Borno state.
Dozens of fighters driving trucks and motorcycles stormed into Kwarangulum late Tuesday, shooting fleeing residents and burning homes after looting food supplies.
Boko Haram and its IS-affiliated Islamic State West Africa Province (ISWAP) faction have recently stepped up attacks on military and civilian targets.
'They killed seven people and abducted a teenage girl in the attack,' local vigilante David Bitrus said.
'They took away food stuff and burnt many houses before leaving,' he said, adding that a church was also burnt.
The jihadists were believed to have attacked from Boko Haram's nearby Sambisa forest enclave, said Chibok community leader Ayuba Alamson who confirmed the toll.
In April, Boko Haram raided Kwarangulum, 10 miles, from Chibok, stealing food and burning the entire village.
Residents had managed to flee before the arrival of the jihadists following tip-off from people who saw the gunmen heading toward the village.
Chibok is the scene of the mass kidnap of 276 schoolgirls in 2014 by Boko Haram which sparked global outrage and drew international attention to the group's notoriety.
Fifty-seven of the girls escaped shortly after the kidnap. Another 107 have been either rescued or released after negotiations while 112 remain in captivity.
Troops have been stationed in Chibok since the kidnap but deadly Boko Haram raids continue in the area.
The decade-long conflict has killed 36,000 people and displaced around two million from their homes in the northeast, according to the United Nations.
The violence has spread to nearby Niger, Chad and Cameroon, prompting a regional military coalition to fight the jihadist groups.
MailOnline