Police authorities in the northern Nigerian city of Kano confirmed Thursday that a German man who was kidnapped in the country four months ago has been killed by his captors.

Kano's Police Information Commissioner Umar Faroukh told dpa that the German man was killed on Thursday morning.

A report by Nigeria's Daily Trust newspaper said the man was killed as security forces were planning a rescue attempt.

The man, who worked for the construction group Bilfinger Berger, was abducted at the end of January. Soldiers had, after months of investigating, traced him to a hideout near the local Bayero University and were about to stage a rescue operation when the victim was reportedly shot dead, reports said.

The kidnappers are reportedly linked to a wing of al-Qaeda in the Islamic Maghreb (AQIM). In March, a video appeared on the internet in which the perpetrators called for the release of the German-Turkish woman who is currently serving a prison sentence for supporting terrorist organizations.

The woman's husband Fritz Gelowicz is a key member of the group who was sentenced in 2010 to 12 years in prison for planning terrorist attacks on German soil.

In the video, which was obtained by the Mauritanian news agency ANI, the victim is shown with his hands tied behind his back, surrounded by masked gunmen.

He is seen calling on “parents, friends and German public opinion” to convince Berlin to “bring to end to the torture of our Muslim sister,” adding that only her liberation will save his life. - Sapa-dpa