An Algerian asylum seeker cleared of plotting to launch a poison attack on London cannot be deported on the grounds that he is a risk to national security, a special court has ruled.

Mr Justice Mitting said that there was an absence of any evidence or intelligence that Mouloud Sihali, 31, had even been a principled Islamist extremist.

The judge, chairman of the Special Immigration Appeals Commission, said: “The commission has found he is not a risk to national security.”

But he said that, on the balance of probabilities, between May and September 2002, Mr Sihali provided and attempted to provide assistance for activities which in fact had a terrorist purpose and that he had lied about them.

John Reid, the Home Secretary, had ordered the deportation of Mr Sihali and three other Algerian terror suspects, known only as U, W and Z, on the ground that they posed a threat to national security.

The commission rejected appeals against deportation in the cases of U, W and Z, ruling that their human rights would not be breached if they were returned to Algeria. It also ruled that, if Mr Sihali were to be deported on grounds other than national security, his human rights would not be breached.

The man known as U is already appealing. Lawyers for W and Z are considering whether there are separate grounds for an appeal.

Mr Sihali was acquitted of charges in the ricin plot trial in April 2005, which alleged that a terror cell planned to distribute the toxin on car door handles in Holloway Road, North London.

He still faces an uncertain future because he is appealing against a decision to reject his asylum application.

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