* Second health care worker murdered by Islamic State in a month
* ICRC regional director confirms group demanded a ransom
* Agency appeals for another health worker, student still held (Adds aid worker's father comments, Nigerian president)
GENEVA, Oct 16 (Reuters) - The family and colleagues of a Nigerian aid worker who was killed by her Islamist militant kidnappers mourned her death on Tuesday as the Red Cross said it had refused to pay a ransom for her release.
The Nigerian government said on Monday a medical aid worker held hostage by Islamic State in West Africa (ISWA) militants was killed after a deadline they had set expired.
The International Committee of the Red Cross (ICRC) later named her as 24-year-old midwife Hauwa Mohammed Liman, who worked in a hospital supported by the Geneva-based aid agency.
A senior ICRC official denounced the killing as "a despicable act of cruelty".
But the organisation had decided not to pay a ransom as it would set a dangerous precedent for the 16,000 aid workers it deploys worldwide, Patricia Danzi, ICRC regional director for Africa, told Reuters.
"We are a humanitarian organisation so we cannot enter into such kind of negotiations. So we always ask for unconditional release. And that's what we did. That was the plea," she said.
The agency had issued a public appeal to her captors at the weekend to spare her life after a threat was received.
The slain aid worker's father, Mohammed Liman, told Reuters that his daughter wanted to serve humanity and that was why she went to a remote area like Rann.
"At the time she was going, I said you should go and treat the people over there, and just after 10 days she was abducted. It is now seven months and 16 days only to be told that yesterday she was executed by the insurgents."
Liman and two other Nigerian aid workers, Alice Loksha and Saifura Hussaini Ahmed Khorsa, were working in Rann when they were kidnapped by ISWA in March.
Khorsa, also a midwife, was killed in September. Loksha, employed by a UNICEF-supported centre, remains a captive, along with Leah Sharibu, a 15-year-old Nigerian student abducted by the group in a separate incident in February.
PEOPLE NEED HELP
President Muhammadu Buhari said the government did everything possible to save Liman's life but all efforts turned out unsuccessful.
Buhari urged the ICRC to keep working in Nigeria and said the government would do all it can to protect its staff and other aid workers providing humanitarian services in the northeast.
The ICRC helps 80,000 mainly displaced people in the northeastern town of Rann.
Danzi said the ICRC was not planning to suspend its operations in northern Nigeria or to withdraw.
"We want to be there for the people that still need our help."
ISWA, an Islamic State offshoot, split from Boko Haram, the main Islamic militant group in Nigeria, in 2016. Its fighters have killed hundreds of soldiers in attacks in northeastern Nigeria in the past few months.
At the entrance to the ICRC headquarters in Geneva, a table was set up with a photo of Liman, along with a white orchid plant, a burning candle and a sign asking staff to write their condolences for her family.
"The most painful thing is that Hauwa and Saifura went to provide humanitarian asistance to the vulnerable amongst us. We are simply telling all humanitarian aid workers that if you go out and they capture you there is nothing that we can do," said Bukky Shonibare, a member of the Bring Back Our Girls movement.
(Reporting by Stephanie Nebehay, Additional reporting Ahmed Kingimi, Adewale Kolawole in Maiduguri and Abraham Achirga in Abuja, editing by Angus MacSwan)
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