Elite British special forces snipers shot dead two terrorists seconds before they murdered a Christian family near Mosul, Iraq, it has been revealed. 

The event is said to have taken place in July, following the fall of Mosul, although details of it only began to emerge last week.

A joint SAS and Peshmerga patrol moved in after they received warning of black-clad gunmen who were targeting Christian families.

The snipers shot dead two Islamic State fighters who were holding knives to the throats of a Christian father and son following their refusal to convert to Islam. 

The execution was just seconds away when the SAS patrol commander ordered two snipers to fire. Both executioners died instantly after being struck from a range of one kilometre.

Seconds later, snipers targeted and shot dead two more gunmen. The rest of the killers then began to panic, a defence source revealed. 

The source also told the Daily Star on Sunday: 'It was a chance encounter. The SAS patrol just happened to be in the right place at the right time.

'The killers were moving around the area executing villagers. Muslim families were accused of being spies and Christians who refused to convert to Islam were beheaded.'

The battle lasted for about half an hour until the terrorists were killed or dispersed and the family were rescued.  

The source told the Daily Star: 'It was a great day for the SAS. They managed to kill up to 15 terrorists and save the lives of a family facing execution.'