They have seen death, they have lost everything and they are too terrified to leave their tents: the trauma suffered by a generation of Sichuan's children could take a decade to repair, psychologists warn.

Even as a few of the quake-struck region's pupils take their first tentative steps back into their classrooms, trauma experts believe a vital sense of trust may be lost. The psychological crisis for the tens of thousands of children left homeless and separated from their towns and villages may be even harder to treat.

Stephen-Claude Hyatt, a clinical psychologist who travelled to the earthquake zone with an orphans' charity, said: “A situation of this magnitude could take a decade to rebuild. This is not something a city can just get over.

“Buildings may go back up in two or three years but there needs to be a psychological rebuilding to go with it. We need to see a reconstruction of the public psyche.” It will be worst, say experts, for children who are sent to new schools far from where they used to live - particularly if they are never reunited with their former classmates.

The entire picture, said Dr Hyatt, was made significantly more complex by China's “one child” policy aimed at curbing population explosion. The Chinese Government, in a rare exception to the 30-year-old policy, said yesterday that families whose child was killed, badly injured or permanently disabled as Sichuan shook will now be allowed to have another.

Because they have no brothers or sisters, Chinese children form exceptionally strong bonds with their school friends. Losing a classmate, said Dr Hyatt, will be the equivalent of losing a parent for many of Sichuan's younger survivors.

Another set of deeply traumatised “virtual orphans” has been created by the death of so many grandparents, said one doctor from Shanghai, who was treating two children for extreme stress at a refugee camp in Deyang. “So many children have parents who migrate to the cities for work and their grandparents take over the role. Psychologically, we must treat children who lose those grandparents as orphans,” she said.

The symptoms of the trauma are visible everywhere in the makeshift tent cities and sports stadiums across the region. Jin, 13, from Hanwang village, is alive only because she made it to a second-storey window in her school and jumped as the floor collapsed. Her parents cannot stop her shaking and crying at night.

As Jin ran in terror from the roar of her swaying school building she saw a friend crushed by falling concrete. She saw another die screaming in pain in the playground. She clings to the memory of a patch of red flowers she planted behind her house - a home that now lies in ruins along with everything else in the village. Gong Xiaoyang, a retired schoolteacher who has retrained to deliver psychological counselling, tries gently to tell Jin how precious her life is. He also takes her parents aside to tell them to go easy on her poor maths scores before the quake. “These children are very scared, very suspicious and very repressed. They have parents begging them not to cry but they can't control their tears so they feel even worse about themselves. It will be a long time before this pain leaves Sichuan.”

Deborah Barry, a child protection adviser for Save the Children, said that the situations in the camps were making the task of helping so many traumatised victims more difficult. “Children imitate, and if parents are sitting around doing nothing because they have nothing, children will take on those feelings and do nothing either. They need a reason to get up in the mornings.”

Times Recommends

• Michael Jackson: Not the final chapter
• Indian Army spends10m rupees on golf buggies
• Brüno toned down for 15 rating