Coptic Christians across Europe are on high alert following last week's attack in Alexandria, Egypt when a suicide bomber detonated explosives outside a church, killing 21 people.

Officers in France are investigating online threats against worshippers, in a country which has the largest Coptic community in western Europe.

Churchgoers across the continent are praying for a peaceful day on Friday, when the Coptic Church celebrates Christmas.

Harry Smith reports from London.