Fourteen-year-old Ghasan Matar won't talk about the explosion that cost him his legs and killed his brother. In fact, six months after the end of the Israeli war on Gaza, he still barely talks at all.

He spends most of his time staring at the walls and a huge poster depicting his older brother against a bloody background of war featuring a Kalashnikov assault rifle and dead Israeli soldiers.

He says he never thinks about the day when the house was hit during heavy shelling of Gaza City's Zeitun neighbourhood. He insists he has no nightmares. "I'm doing fine," he says, and then clams up.

"He's very traumatised. He doesn't speak, tries to act like nothing happened," says social worker Nisrin Ramadan during a visit to the boy's crumbling brick home.

"There are many cases like this of deep shock and loss of hope," says Ramadan, who works with the Society for the Physically Handicapped.

More than 300 children were among the 1,400 Palestinians killed and many more were wounded during the 22-day Israeli offensive that ended on January 18, according to Palestinian figures.

And experts say a vast majority of the children who make up more than half of Gaza's 1.5 million population, will bear the psychological scars for years to come.

"Children here have lost joy in life. They can laugh but there is no joy. They are unable to maintain hope," says psychiatrist Eyad Sarraj, who heads the Gaza Community Mental Health Programme.

Seven-year-old Ahmed Salah al-Samuni smiles timidly as he is tossed a green plastic ball but quickly loses interest, instead digging his nails into a couch in a brightly coloured room used for psycho-social counselling sessions.

"I remember that Israelis came and ordered us out. Shells were fired," he says when asked what he remembers of the war.

"Grandmother and grandfather are dead," he says, going on to list about 10 others who died when his house was bombed. In all, 29 were killed in the attack, 18 of them from his direct family.

"I love Azza and want her back," he says of his two-and-a-half year-old sister who was among the dead.

After the attack, he lay in a pool of blood. It's only when he cried out for his mother that she realised he was still alive.

A large scar runs across his face, another along his hip. His nose is still deformed from the shrapnel wounds.

Just a few months ago he had regular fits of rage, when he'd beat his brothers and break whatever was in his path.

"He'd scream out at night: 'The Jews are coming to kill me'," his father says.

His psychological scars are also starting to heal. "But it's a long process. He has seen so many dead bodies," says counsellor Sabri Abu Nadi.

A huge number of children went through "horrible situations" during the war, says Saji Elmughanni, the Gaza spokesman for the UN children's agency UNICEF. "Nowhere was safe" in the overcrowded sliver of land wedged between Israel, the Mediterranean and Egypt.

"All children here went through some degree of exposure to violence."

Many bury their feelings deep inside.

Njood Basal, 14, who suffered serious shrapnel wounds to the head, spends much of her time sitting on her bed in a room where light filters through holes in the tin roof.

She chats on the Internet with friends "in other countries, mainly the West Bank."

"I don't tell them what happened ... they ask, but I always change the subject. I feel upset when I talk about the situation."

Outside her house, a poster depicts her cousin Talat Basal. Her family says he was a "martyr," a member the Ezzedine Al-Qassam Brigades, the military wing of the Islamist Hamas movement that rules Gaza.

Psychiatrist Sarraj says the exposure to extraordinary levels of violence is certain to turn many of today's children into tomorrow's extremists.

"I'm sure there will be a new breed of militants, they'll want a more militant group than Hamas to feel protected," he says.

Reminders of the war that Israel launched to halt rockets fired by Hamas and other Palestinian armed groups are everywhere: buildings reduced to rubble, shell-scarred facades, charred car wrecks.

At night, firing can be heard from the Israeli naval ships that ensure fishermen don't venture more than a few kilometers (miles) from shore.

Mental health experts say many children in the tiny coastal enclave still live in fear of renewed military attack.

"Whether consciously or unconsciously, the fear of another war is always there," says Sarraj.

Awad Sultan, 12, lives in one of dozens of tents set up north of Gaza City to house families who lost their homes in the war.

He says he still has nightmares. "Israeli soldiers try to catch my dad and destroy houses."

What was once his family home is now just rubble.

The bicycle he loved riding is a charred piece of wreckage. Now he plays with other kids from the camp in a large tent set up by social workers.

"We have fun, but what's the use. We come back and think about the war."