COLOMBO, Sri Lanka – More than 1 million children around the shores of the Indian Ocean are at risk of disease, abuse, or exploitation, aid agencies said last night.

As the focus of concern shifted to helping the vulnerable “tsunami generation,” international charities said that children, had suffered disproportionately in the disaster.

Forty percent of the 146,000 people killed by the giant waves are believed to be children and the survivors, many of them orphaned, are most prone to disease, abuse, and exploitation.

Carol Bellamy, the executive director of Unicef, the United Nations Children’s Fund, told an international conference she was not satisfied “that the global relief effort is focused enough on the more than a million children made vulnerable by this calamity.”

She said: “The relief effort everywhere must focus on keeping children alive. This means clean water, adequate sanitation, basic nutrition, and routine medical care.

“Our second priority is caring for separated children. We must find those who have lost their parents and reunite them with their extended families and communities.

“Third, our efforts must ensure that children are protected from exploitation. In tumult like this, when families are broken apart, when incomes are lost, when dignity and hope are in short supply, children are more vulnerable to abuses.”

In the many camps set up to house Sri Lanka’s 800,000 displaced people, unconfirmed reports of sexual abuse are being investigated.

The Sri Lankan Medical Officers’ Association said it had heard of several cases of children being sold and urged the government to convert parts of hospitals to child-only wards to house them away from adults.

There were also fears that the country’s orphanages would be filled beyond capacity as fathers who had lost their wives felt unable to cope and sent their children to institutions.

In the south of the island near Galle, where many families relied on fishing, aid workers said that, even where both parents had survived, impoverished and homeless parents might choose to send their children to orphanages.

In the chaos that has followed the tsunami, some of those orphaned have been unofficially adopted, either by relatives or parents grieving the loss of their own.

Women’s groups have called for all children separated from parents to be registered with the police, and the government is urging those wishing to adopt to go through the formal procedure so that adequate vetting can be carried out, or risk prosecution.

More than a week after the catastrophe, Sri Lankan officials still cannot put a figure on the children affected by the tsunami, which killed 30,196 in the country, with almost 4,000 missing.

Many orphanages house children who have one or more parents but who have been sent there for a better education. There is a long tradition of sending children to institutions.

In one orphanage in Mullaittivu, in Tamil Tiger-controlled territory in the northeast, 75% of the children belong to Tamil Tiger widows who left them there while they joined the anti-government rebellion.

Harendra de Silva, the head of the Sri Lankan National Protection Authority, said: “It is almost impossible to give protection to all the women and children in the camps. The children are especially vulnerable.”

In southern India, aid groups are concerned that orphans are being farmed out among greedy relatives.

“These orphans are precious to their relatives and even others not related for the relief money that is being offered by the government,” said S. Vidyaakar, of the Madras-based organization Helping Hands, which cares for destitute children. The organization advertised in newspapers offering to take tsunami orphans into care but received no response.

Mr. Vidyaakar said he feared that many of the orphans would be abandoned after the families had received the compensation payments.

The orphans’ nearest relatives have been promised $4,700. The money is to be placed in bank accounts for the children until they are 18. But the interest – a large amount in devastated fishing communities – will be signed over to the relatives for the children’s maintenance. Nearly 6,000 people were killed in the Nagapattinam district of Tamil Nadu state, most of them fishermen and their children who lived within a mile of the Bay of Bengal.

Many of the children had been playing on the beach when the waves struck. In some villages, up to 500 children – an entire generation – were wiped out, leaving no one to carry on the traditional industry.

Thailand, where half the victims were tourists, has reported 300 orphans.

A spokesman for Unicef, Martin Dawes, said: “This disaster is so horrendous, so overwhelming. This tsunami generation will have to be looked after.

“They are marked for life. Some will cope; some will be absolutely finished or phenomenally badly affected.”