Updated

Islamic State-linked extremists in Nigeria have killed another abducted health worker despite an urgent plea from the International Committee of the Red Cross to spare her life, Nigeria's government said late Monday.

The statement did not say which of the two abducted health workers, both women, was killed. The death comes a month after a third health worker was killed by the same group, the Islamic State West Africa Province. It has become the largest IS-linked extremist group in Africa.

All three workers were seized in March in Nigeria's northeastern community of Rann, where thousands have sought shelter from the extremist threat that includes the Nigeria-based Boko Haram insurgency.

There was no immediate comment from the ICRC, which on Sunday said "we urge you for mercy" and noted that a 24-hour deadline was counting down. The global aid organization urged Nigerian authorities and others who might have influence to help.

The statement by Nigeria's information minister on Monday said the government was "shocked and saddened" and would continue to work for the release of other captives.

"The federal government did all within its powers to save her life," the statement said, adding that the government had kept the "line of negotiations" open since the abductions.

The killing in September of Saifura Hussaini Ahmed Khorsa led to outrage. She was abducted along with Hauwa Mohammed Liman, who was working in a local hospital supported by the ICRC, and Alice Loksha, a nurse who worked at a center supported by the U.N. children's agency.

The ICRC, which does not pay ransoms, earlier said it had not been directly involved in discussions on the extremists' demands.

The same group of extremists also is holding Leah Sharibu, a student seized in a mass abduction in February. She remains captive while more than 100 of her fellow students were released because she is Christian. Her mother in recent weeks has said her life was in danger.

Nigerian President Muhammadu Buhari, who declared that defeating extremism was a top priority when he took power in 2015, in recent days sent three Cabinet ministers to meet with the families of Sharibu and the abducted health workers, his office said.

Buhari last month called the killing of Khorsa "an act of extreme barbarism; utterly reprehensible and inhuman."

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