Belgian police are hunting for a teenager who has called for "the murder of all Christians" in a video posted on a French website.

The 15-year-old, who has not been named, says in Arabic "Oh Allah, destroy the odious Christians" in the film shot in Verviers, the scene of a successful anti-terrorism operation last year. The boy, who has been identified and is on a list of radicalised individuals, adds: "Oh Allah kill them all. Don't spare any of them."

The Mayor of Verviers, Muriel Targnion said the video was being taken seriously and has asked the police to trace the boy "as a matter of urgency."

A police source said that the teenager, who is the son of a local radical imam, posed a potentially "serious threat" to the public and they wanted to trace him "as soon as possible."

Regional Belgian newspaper La Meuse reported that the teenager is the son of a local radical imam, El Alami Amaouch, who is currently facing deportation to the Netherlands.

Amaouch is reportedly imam at a mosque in the village of Dison, near Verviers, and has duel Dutch-Moroccan nationality.

Belgium's Minister for Asylum and Migration, Theo Francken, said the authorities had repeatedly tried to extradite Amaouch to the Netherlands but he had appealed and this had delayed the deportation. "We have been trying to get him out of the country for the past year but he has appealed," Francken told VRT News. "I can only hope that the Aliens' Council deports him quickly".

Francken claimed that the imam was the "spiritual father" of a terrorist cell in Verviers, adding: "It seems that it runs in the family."

In January 2015, police disrupted a suspected extremist cell in Verviers. The authorities said that the aim of the terrorists was to kidnap a high-ranking Belgian official and behead him live online.

Last month, a Belgian priest was stabbed after letting an asylum seeker into his home ot take a shower. There was no suggestion that the incident was terrorism-related.