Schoolchildren have exploited loopholes in Britain's arms controls by importing torture equipment including thumb and wall cuff restraint devices and a Chinese "sting stick" - a metal bar covered with spikes.

All that teenagers from Lord Williams's school in Thame, Oxfordshire, needed was a letterhead, a mobile phone, an email address, and a little money. They also set up a separate company in Ireland to avoid British controls on the sale of small arms.

The government says it is opposed to any trade in torture equipment, but bans only those items mentioned on a published list. The wall cuffs from Poland, thumb cuffs from Taiwan, and sting stick from China do not appear on the list.

The pupils set up two companies, Williams Defence and Williams Defence (Eire). Through their Irish company they arranged deals to destinations covered by British and other national trade embargos, including the sale of Pakistani grenade launchers to Syria, Turkish guns to Mali, and South African rifles to Israel.

The Thame children got quotes but did not go ahead with the deals. However, children from a school in Portloaise, near Dublin, succeeded in buying electric shock batons from Korea and leg irons from South Africa.

The ease with which British controls on trade in torture equipment and small arms can be evaded is exposed in a Dispatches programme, After School Arms Club, presented by Mark Thomas, to be broadcast on Channel 4 next Monday. "It should not be legal, and yet we've proved that children, who by law are not allowed to drink alcohol, can broker arms from countries along a trade route from Poland to China, Israel to South Africa. And many of these arms are used against - or tragically even by - children," said Maddy Fry, 16, a pupil at Lord Williams's school.

George Lear, head of citizenship at the school, said: "We were stunned by what we could achieve. Nobody questioned us at any stage." Roger Berry, chairman of the Commons quadripartite committee which monitors export controls, said yesterday that Britain was in the absurd position where children could freely import equipment that could be used in torture while anyone could be arrested for carrying "offensive weapons".

The pupils presented Malcolm Wicks, minister responsible for export controls, with the sting stick outside the Commons. He has asked them for a report on how they managed to import the torture equipment so easily.