Berlin attacker encouraged teenage nephew to kill for Isis

The target was believed to be the police officer husband of one of Anis Amri's sisters

Anis Amri, man named as wanted in connection with the Berlin Christmas truck attack, Berlin, Germany (Rex)

The Berlin market attack suspect reportedly encouraged his 18-year-old nephew to kill his police officer uncle so he could prove his allegiance to Isis.

Anis Amri, 24, is believed by police to have driven a truck through a Christmas market in the German capital, killing 12 people and wounding 56. He was shot dead in Milan in a clash with police.

Before his death, he is alleged to have urged his teenage nephew Ferjan Fadi to kill so he could prove his allegiance to Isis. A police source told The Telegraph that the target was the police officer husband of one of Amri’s sisters.

​Fadi was arrested in his hometown of Oueslatia, where Amri also hails from, this weekend. The impoverished community is around 100 miles south of the North African country’s capital, Tunis, where two other men believed to be connected to Amri, were also detained.

The three suspects were members of a "terrorist cell" that was "connected to the terrorist Anis Amri who carried out the terrorist attack in Berlin", according to a statement fromTunisia's Interior Ministry.

Amri appears to have recorded a video message pledging allegiance to Isis and vowing to take revenge on European "crusaders" for bombing Muslims, according to footage released by the Isis-affiliated Amaq agency.

In the video, a man claiming to be Amri says: "My message to crusaders bombing Muslims everyday... Their blood will not go in vain. We are a nation behind them and will take revenge for them.

"I call on my Muslim brothers everywhere... Those in Europe, kill the crusader pigs, each person to their own ability.”

Amri’s family have called for his remains to be sent to Oueslatia and asked authorities for details about his role in the attack.

But Tunisian Foreign Ministry spokesman Bouraoui Limam said that while he expected the body to be repatriated, it would "take a while" because Italian, German and Tunisian investigators needed to carry out examinations first.