The Ministry of Defence said the jets were part of a 'major' coalition raid on a complex of bunkers and tunnels near Kirkuk, in northern Iraq, in support of Kurdish ground forces.

Reconnaissance identified a well concealed network of fighting positions and underground facilities, and confirmed that the site was well removed from any civilian communities.

ISIL extremists were believed to have retreated to the area away from advancing Kurdish peshmerga.

The MoD said aircraft from seven nations conducted a 'comprehensive and closely coordinated attack' on complex in the early hours of Wednesday. They RAF Tornado GR4 aircraft, carrying Paveway IV laser-guided bombs.

Defence Secretary Michael Fallon said: 'RAF missions continue to play a crucial role in support of Iraqi ground operations.

'This morning's strike will have dealt a blow to the ISIL network in a key location, thus limiting their ability to pursue their brutality against the civilian population of Iraq.

'This is further evidence of the UK's significant role within the coalition, and is one strand of a measured approach to degrading ISIL by an air campaign while also supporting the Iraqi forces through training and development.'