Boko Haram pledges allegiance to ISIS

The militant group Boko Haram has pledged allegiance to the Islamic State, according to reports citing an audio message.

The message, published on Boko Haram's Twitter account cannot be immediately verified. According to reports, it was likely to have been recorded by the group's leader.

Jihadist monitoring group SITE said that it was Boko Haram leader Abu Bakr Shekau who formally pledged the allegiance to Abu Bakr al-Baghdadi, the self-proclaimed leader of the Islamic State, Reuters news agency reported.

In his speech the Boko Haram leader reportedly said the group would 'hear and obey' the Caliph 'in times of difficulty and prosperity'.

Last June ISIS jihadists declared the captured areas a new Islamic State - a caliphate.

The ISIS leader Abu Bakr al-Baghdadi proclaimed himself a caliph and urged other radical Sunni groups to pledge their allegiance.

Shortly afterwards, the head of Nigeria's Boko Haram radicals vowed support for the Sunni Islamic State extremists and other Islamist groups in a video statement.

In November, numerous jihadists from Egypt, Algeria, Libya and other countries pledged allegiance to the Islamic State. This January, Afghani and Pakistani militants also joined the Islamic State, claiming they constituted its province.

Boko Haram atrocities are estimated to have left at least 13,000 dead since the insurgency began in 2009. Around 1.5 million people have become internal refugees due to the violence, soaring from 600,000 in the past six months, according to the UN.

The group was founded in 2002 but its increasing radicalization started after an uprising in 2009 when the militants began carrying out massacres, kidnappings and raids. Agency report