Children as young as nine have been left "petrified" that Britain could be hit by a terror attack, a leading charity has warned.
Youngsters contacting the NSPCC's Childline service have suffered panic attacks, anxiety and insomnia triggered or exacerbated by atrocities around the world.
In the last year, the facility has handled 660 counselling sessions about terrorism, with children discussing conflicts in the Middle East and often mentioning Islamic State - also known as Isis.
It is the first year the service has specifically recorded contacts concerning terrorism after a surge in the wake of the Paris massacre. Extremists killed 130 people in mass shootings and bomb attacks in the French capital a year ago.
Subsequent atrocities in Brussels, Orlando and Nice all triggered a higher volume of calls to Childline.
Where the age was known, a fifth of contacts about terrorism were from children aged 11 and under, while girls were twice as likely as boys to seek support from the service.
Many youngsters feared the outbreak of war and frequently reported that they were afraid of a terror attack hurting their families.
One 11-year-old boy said: "I'm so scared at the moment with everything going on.
"I constantly feel anxious about terrorism and think that Isis is going to attack the UK soon. I am really worried that they will get someone in my family. I haven't been sleeping because it is all I can think about."
A girl, 14, said: "My anxiety is becoming worse after the terrorist attacks. I'm really worried something like this could happen in London."
Attacks overseas in recent months have heightened fears Britain could be targeted. The official threat level for international terrorism in the UK is severe, meaning an attack is "highly likely".
NSPCC chief executive Peter Wanless said: "These vicious attacks have seared themselves into the consciousness of children, who tell us how petrified they are of these sadistic atrocities happening on UK shores.
"The past 12 months have been stained by these bloody events and it is little wonder that young people are so frightened about terrorism.
"Sadly we now live in a world where the months are punctuated by these inhumane attacks, so it is vital that we do not brush young people's fears aside.
"Instead, we must listen to their worries and reassure them that there are people doing everything they can to keep us all safe.
"Childline is always hear to listen to a child, and our helpline can offer adults advice on how to comfort and talk to children about difficult topics."
::Any young person who is worried can call Childline free and anonymously on 0800 11 11 and adults who want advice on how to talk to their child about terrorism can call the NSPCC Helpline on 0808 800 5000.