The disclosure means that a decision on whether to allow new exports, expected to test Robin Cook's new ethical foreign policy, may not now have to be made in the near future.
An announcement had been expected within the next few weeks on whether a new consignment of 16 fighter aircraft would be allowed to go ahead. It now appears that Ian Lang, the former President of the Board of Trade, authorised the exports last November.
Campaigners have argued that Britain should not sell arms to the Suharto regime, claiming that they have been used to attack civilians in occupied East Timor. They say Indonesia has one of the world's worst human rights records.
Barbara Roche, the Trade minister, said in answer to a parliamentary question on Friday that Mr Lang had been "wrongly advised" last November when he said that licences for 16 further Hawk jets fulfilled a contract drawn up in 1993. In fact the 24 jets sold in 1993 had already been given licences and Mr Lang was licensing a further 16 jets sold in 1996.
The mistake appears to mean that Mr Cook has no imminent decision to make on the export of Hawk jets to Indonesia. Ministers are at present drawing up new criteria designed to cover the export of arms to repressive regimes, which are expected to centre on the likelihood of them being used against dissidents or civilians.
Government sources have been reported as saying that no satisfactory evidence has been produced that the jets have been used in East Timor. They also said that they will not revoke existing export licences because to do so would mean paying compensation to manufacturers.
Yesterday Barry Coates, director of the World Development Movement, said the revelation had proved fortunate for Mr Cook. "The first test of the new ethical foreign policy is not immediate now, but we don't think that ought to let the Foreign Office off the hook. We want a clear statement to say, in future, orders like this would not be permitted," he said.
The criteria being set were unfair because it was almost impossible to prove the Hawks were being used in East Timor, he added. The aircraft were designed for stealth and, even if they were photographed, it would be impossible to prove where they were. Large numbers of eye-witness accounts should be enough to prevent any more exports.
A legal opinion prepared for WDM by Bindman and Co says the Government would not have to pay compensation if it revoked the licences because of a catch-all clause allowing them to be cancelled at any time.
Menzies Campbell, the Liberal Democrat defence spokesman, has asked Robin Cook to cancel invitations to three senior Indonesian military officials to come to the Farnborough defence show in September.
"Withdrawing such invitations and cancelling export licences would show the Government is serious," he said.
A spokesman for the Department of Trade and Industry said: "A mistake was made and the House was misinformed, so we took the opportunity to correct the situation. We got this wrong."Reuse content