Video purportedly by leader of Nigeria group posted after female Islamists suicide bombers kill at least 50 in coordinated attacks in Maiduguri

The main gate to the Monday Market, Maiduguri, where a suicide bomb attack took place on Saturday. Photograph: Tunji Omirin/AFP/Getty Images

by Daniel Boffey, The Guardian

Nigeria’s militant Islamist group Boko Haram has sworn allegiance to Islamic State, which rules a self-declared caliphate in parts of Iraq and Syria, according to a video posted online. The pledge came in an Arabic audio message with English subtitles alleged to have come from Boko Haram leader Abubakar Shekau and posted Saturday on Twitter, according to the SITE Intelligence monitoring service.

“We announce our allegiance to the Caliph of the Muslims … and will hear and obey in times of difficulty and prosperity, in hardship and ease, and to endure being discriminated against, and not to dispute about rule with those in power, except in case of evident infidelity regarding that which there is a proof from Allah,” said the message.

The video script identified the caliph as Ibrahim ibn Awad ibn Ibrahim al-Awad al-Qurashi, who is better known as Abu Bakr al-Baghdadi, the leader of Islamic State and self-proclaimed caliph of the Muslim world. Baghdadi has already accepted pledges of allegiance from other jihadist groups in the Middle East, Afghanistan, Pakistan and north Africa.

Boko Haram has been waging a six-year military campaign to carve out an Islamic state in northern Nigeria.

Earlier on Saturday, four bomb blasts killed at least 50 people in the northeastern Nigerian city of Maiduguri in the worst attacks there since Boko Haram militants tried to seize the town in two major assaults earlier this year. Female suicide bombers believed to be acting for the group launched a series of attacks in markets, while another detonation was reported at a bus station.

In a fifth incident, a car bomb exploded at a military checkpoint 75km outside the city, wounding a soldier and two members of a civilian defence unit. The attacker in this incident had wanted to reach Maiduguri, a police officer at the scene said. In total, it is believed 58 people have been killed in the incidents and 143 wounded, but both figures were expected to rise.

Maiduguri was once the base of the Islamist group, which has been conducting a campaign of violence pushing for Islamic rule in Nigeria. At least 13,000 people have so far been killed in the campaign. After being pushed from the city last year, the militants retreated to the nearby Sambisa forest, from where they launched attacks on villages and towns in the region, taking over swaths of territory.

Last month experts warned Boko Haram was likely to increase its attacks on civilian targets in response to the successful campaign by government forces to retake several of the group’s former strongholds.

The first attack on Saturday occurred at the city’s Baga fish market at around 11.20am, according to Abubakar Gamandi, head of the fisherman’s union in Borno state. “A female suicide bomber exploded as soon as she stepped out of a motorised rickshaw,” said Gamandi, who was at the scene. “Eighteen people were killed.” A market trader, Idi Idrisa, said: “I saw many bodies and several badly injured”.

About an hour later a second explosion rocked the Post Office shopping area near the market, leaving many casualties. A further series of bombs then rocked what is known locally as the Monday market, the biggest in Maiduguri, killing at least 15.

A trader there told the BBC that two other female bombers seemed to have targeted the market. One had a bomb strapped to her body that detonated as she was being scanned at the entrance gate, he said. Another woman was said to have exploded a bomb she was carrying in a bag a few feet away.

A fourth bombing came shortly after 1pm at the nearby busy Borno Express bus terminal, where witnesses said about 12 people were left either dead or injured. A survivor of the first blast said it occurred when a boy aged about 16 moved into a crowd by the gates holding what looked like a remote control. Security officials were about to stop the teenager when there was a blast. The witness said he was blown over by the impact and when he came to he saw at least six bodies.

A vigilante leader in Borno, Danlami Ajaokuta, whose civilian fighters have been working with the military in the region to fight Boko Haram, said security forces had ordered the closure of all businesses in the city given the apparently coordinated nature of the bombings and the fear there could be more. The state’s justice commissioner, Kaka Shehu, confirmed the attacks but declined to discuss casualties.

Last week, President Goodluck Jonathan said the tide has “definitely turned” against militant Islamists as Nigerian troops and their regional allies recapture territory.

Boko Haram has recently launched attacks on villages in Cameroon and Niger, as Nigeria’s neighbours are forming a multinational force to confront the spreading Islamist uprising.

Chad’s President Idris Déby last week said his forces knew the whereabouts of Boko Haram leader Abubakar Shekau and warned him to surrender or face death. Shekau’s fighters are massing at a headquarters in the northeastern town of Gwoza, in apparent preparation for a showdown with multinational forces, according to witnesses who escaped the town. An intelligence officer told Associated Press that they were aware of the movement, but that the military is acting with care as many civilians are still trapped in the town and Boko Haram is laying land mines around it.

Nigeria’s presidential and parliamentary elections have now been postponed by six week to 28 March to give troops time to push back the militants. Shekau has vowed to disrupt the vote and widespread unrest, especially near polling stations, could prove disastrous. Hundreds of thousands of people displaced by the conflict are living in Maiduguri, swelling the city’s population to well over two million.