A German engineer kidnapped in northern Nigeria about five months ago has been killed during a failed rescue attempt, officials have revealed.
Kano state police commissioner Philemon Ibrahim Leha said that the attempted operation to free Edgar Fritz Raupach took place in the early hours of Thursday in the state capital of Kano, but did not immediately provide further details.
A military official told the AP news agency that five people, including a woman, were killed in the operation to free Raupach.
It was unclear whether Raupach was killed before or during the rescue operation.
Al Jazeera's Yvonne Ndege, reporting from the capital Abuja, said that there have "been no official statement from the Nigerian police over what went down this morning".
"Officials and witnesses have described an hour long battle outside a home in Kano ... security officials say that Edgar was held captive in this house and when they entered the house they found that he had been killed by his captors," she said.
In Berlin, a Foreign Ministry spokeswoman said the ministry could not currently confirm that the hostage had been killed, and that the ministry's crisis unit and the German embassy in Abuja were working to clarify the situation.
Gunmen kidnapped Raupach in January from Kano, Nigeria's second-largest city, where he worked for Dantata & Sawoe Construction Company.
Police said his abductors had taken him from a construction site.
Meanwhile, authorities said on Wednesday that an Italian national had been abducted Monday in the western state of Kwara.
Kidnappings are rare in Kwara but the abduction comes as attacks targeting expatriates working in Nigeria's Muslim northern and central regions are reportedly on the rise.
"This kind of kidnapping of expatriates working for engineering or construction firms is becoming more common unfortunately," Ndege said.
Al-Qaeda in the Islamic Maghreb (AQIM) had released a statement in March claiming they had Raupach, as well as a video showing him disheveled and asking in German and English for his country to help win his freedom.
The group demanded that German officials release Filiz Gelowicz, a German woman convicted last year of supporting a foreign terrorist network.
Gelowicz's husband was among a group convicted of plotting unsuccessfully to attack US soldiers and citizens in Germany.
German officials subsquently released Gelowicz from prison in late April on probation after she served two-thirds of her sentence.
'Release our brother'
In May, an unsigned advertisement appeared in the Daily Trust, a Nigerian newspaper, showing a photograph of Raupach and messages in Arabic and English calling for him to be released.
"Your sister Uma Saifullah Al-Ansariya (Filiz Gelowicz) is free since two weeks,'' the advertisement read. "When do you release our brother Edgar? His friends are waiting for him.''
It was not clear whether German authorities authorised the message.
AQIM grew out of organisations fighting the Algerian government in the 1990s. The group's real impact in Nigeria is said to be felt with the rise of Boko Haram, an armed Islamist group.
The sect began gun attacks from the backs of motorcycles, but, last year, it started escalating its attacks with a string of suicide bombings targeting churches, government buildings, and the UN headquarters in Abuja.
Security officials and diplomats say Boko Haram has loose links with AQIM and may have received training and some funding from the group.