Refugee workers say that the increase is due in part to better detection but also to the special threat posed to young boys and girls in countries at war.
Tim Kirkhope, the minister responsible for immigration, said the Home Office was planning a crackdown on the arrivals which were costing the British taxpayer an estimated pounds 12m a year. Mr Kirkhope condemned the practice as "immoral" and said he was angry at the way parents were putting children on flights to Britain to "seek a better future".
Mr Kirkhope is planning to use the controversial Immigration and Asylum Bill, when it becomes an act, to speed up the consideration of asylum cases. He is also seeking agreements with some of the main countries involved to stem the flow of unaccompanied children.
Many of the children are allowed to stay, supported by local authorities' budgets for education and social services, because the immigration authorities cannot trace their parents in their country of origin.
Agreement was reached with the Sri Lankan authorities last week to send back unaccompanied children. Ethiopia has agreed to take back children, but only where both parents can be traced.
Immigrants' groups are likely to protest that the children are escaping from danger in their own countries. But Mr Kirkhope believes many are economic migrants, sent by their parents to Britain because they cannot support them at home.
The figures show that famine and civil war have a significant impact on the numbers.
The country with the highest number of children seeking asylum is Somalia, which had 79 last year. There were 54 from Sri Lanka and 31 from Sierra Leone. The issue is certain to inflame the row over the Immigration and Asylum Bill, which is due for a second reading in the Commons on 12 December. The number of unaccompanied children arriving in Britain seeking asylum has risen from 185 in 1992 to 357 in 1994. This year's figure is expected to reach 600. The Home Office estimates it costs Britain pounds 20,000 per child per year.
"I am angry that anybody anywhere should send a child to an uncertain future by putting them on a plane," Mr Kirkhope said. "It is immoral".