Three British Special Forces soldiers were injured in a firefight with 30 ISIS militants in Iraq, the Mirror newspaper reported on Saturday without providing any details about its sources.
The Ministry of Defense said it did not comment on Special Forces operation.
The Mirror said that the SAS and SBS units were on a secret mission deep inside enemy territory in northern Iraq when 30 ISIS fighters opened fire on them with machine guns mounted on American-built Humvees.
The men injured by bomb blasts during the 25 man patrol in northern Iraq are believed to be the first British casualties in the conflict, the Mirror reported.
The report further said the covert Special Forces patrol by British, German and U.S. Special Forces aimed at identifying ISIS positions outside Mosul and spotting weak areas in the defenses of the militant group.
ISIS fighters involved in the incident were all killed in the 15 minute battle and an airstrike that followed.
A unit of German commandos fired an armor piercing missile fired by killing every extremist on location.
The wounded soldiers hit by shrapnel were treated at the scene before being airlifted out by helicopter to a UK facility for recovery, the report said.
In addition to hundreds of British soldiers officially training security forces in Iraq in an alleged hunt after ISIS, Britain is also taking part in air strikes on ISIS-held areas in Iraq and Syria.