Hauwa Mohammed Liman, who worked in Red Cross-supported hospital, had been held hostage since March

This article is more than 1 year old

This article is more than 1 year old

Islamist extremists in Nigeria have killed a medical aid worker held hostage since March.

Hauwa Mohammed Liman, 24, was killed by militants from a faction of Boko Haram after a deadline expired, authorities have said.

Liman, a Nigerian who worked in a hospital supported by the International Committee of the Red Cross (ICRC), was one of three aid workers kidnapped by extremists during a raid on the town of Rann in the restive north-eastern Borno state.

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A second aid worker, an ICRC midwife, was killed in September. The surviving hostage worked as a nurse in a centre supported by Unicef.

Boko Haram, which has also been known as Islamic State in West Africa, has been waging a deadly campaign in north-eastern Nigeria for almost a decade.

The militants said in a video posted online last month that they would kill at least one hostage once a deadline due to elapse on Monday had passed. It is unclear what demands, if any, the extremists made for the release of the hostages.

In a video released in recent hours viewed by local reporters, the militants said Liman deserved to be killed because she had abandoned Islam by working for the ICRC.

The clip had also referred to Leah Sharibu, a 15-year-old who was one of more than 100 schoolgirls abducted by Boko Haram from a boarding school in Dapchi in February.

While other students were released weeks after the abduction, Sharibu, the only Christian among them, was held back for refusing to convert Islam. The militants said the teenager would be kept as a slave.

Nigeria’s military and government have repeatedly said they are on the point of defeating Boko Haram and its various factions. However, raids on military bases have continued, inflicting significant casualties. The death toll from one assault on a Nigerian army post on the border with Niger last month reached 48. A similar attack was foiled this weekend, officials said.

Boko Haram uses kidnapping as a weapon of war, abducting thousands of women and girls and forcing young men and boys to fight in their ranks.

Profile Who are Boko Haram? Show Hide Commonly known as Boko Haram, the Islamic State in West Africa is a terrorist organisation based in Northeast Nigeria. Formed in 2002 as Jamā'atu Ahli is-Sunnah lid-Da'wati wal-Jihād meaning “Group of the people of Sunnah for Dawa and Jihad”, the term Boko Haram is loosely translated as ‘Western education is forbidden’ or ‘Western influence is a sin’. Boko Haram started an armed rebellion against the Nigerian government in 2009. Their activities have included suicide bombings and the kidnapping of female students from a college in Chibok in 2014. A mass prison break-out in 2010 swelled their ranks. Their insurgency has also spread into neighbouring Cameroon, Chad and Niger.

In 2015 a coalition of troops from those three countries, alongside Nigerian forces, mounted a concerted effort to push back against Boko Haram. For their part, since 2015, Boko Haram has aligned itself with Islamic State. The UN estimates that at least 20,000 people have been killed in the conflict to date, but that is widely held to be far below the true number. At the peak of its strength it held territory equal to the size of Belgium Nigeria’s President Muhammadu Buhari and his generals have repeatedly declared that they have “beaten”, “defeated”, “technically defeated”, “routed” and “broken the heart and soul” of Boko Haram. Studies suggest casualties have dropped drastically in recent years. But the suicide bombings, child abductions and displacement of the local population continues. Estimates of the group’s strength vary between 4,000 and 20,000 fighters, and the number of people who have fled Boko Haram’s territory in the Lake Chad Basin is thought to be in the order of 2.4 million.

The mass abduction of more than 200 schoolgirls from Chibok, Borno state, in April 2014 brought global attention to the insurgency and was widely condemned. More than 100 girls have since been released or found.

Lai Mohammed, the Nigerian information minister, said the government was “deeply pained” by the latest killing but pledged to “keep the negotiations open and continue to work to free the innocent women who remain in the custody of their abductors”.

The presidency tweeted “that the federal government did all within its powers to save her life”.

Analysts say Boko Haram is a fragmented coalition comprising different factions, rather than a single organisation. One major rift saw the group blamed for the recent deaths split from that led by Boko Haram’s veteran leader, Abubakar Shekau, after arguments over his indiscriminate targeting of civilians in raids and suicide bombings.

Analysts believe this breakaway faction has a new hardline leadership after another internal struggle and is responsible for the recent killings.