Amber Rudd, the Home Secretary, must now consider what options she has left

An Algerian terror suspect, who has been in Britain for more than 20 years, cannot be deported because he has kept his identity secret.

The Home Office's attempts to remove the man have been thwarted yet again after an appeals panel ruled in his favour.

Despite twice being categorised as a threat to national security, the Algerian is still in the country after entering the UK illegally in 1993.

Since then the man, known only as 'B' in court, has repeatedly failed to give his name - meaning the authorities have been unable to identify him.

He has given the false identities of 'Nolidoni' and 'Pierre Dumond' to keep the Home Office from having his true name.

Judges have made court orders demanding he identify himself to no avail.

In one case the judge decided to send him to prison for four months in contempt of court because of his lack of cooperation.

The court have also strangely imposed an anonymity order on the man, despite his identity not being know, The Sunday Telegraph reports.

In 2000 he was ruled as being 'actively involved in the procurement of telecommunications equipment and in the provision of air time for satellite telephones for the purpose of terrorist activity.'

Two years later he was detained over terror allegations and spent four months in the high-security Broadmoor Hospital.

In 2005 after being released he was given a control order under anti-terror legislation as Home Office bosses continued to try and deport him.

And in 2008, a judgement found that he had 'played a leading role in facilitating communications for Algerian terrorists, as well as being responsible for the procurement of false documentation and high technology equipment'.

The man's lawyers have warned he would face torture if sent back and have used the Human Rights Act to defend him.

Tens of thousands of pounds of taxpayers' money has been spent on his legal team through legal aid.

The Home Office's attempts to remove the man have been thwarted yet again after an appeals panel ruled in his favour

Amber Rudd, the Home Secretary, must now consider what options she has left in appealing the decision made by the Special Immigration Appeals Commission (SIAC).

Lawyers for the Government have warned they will now struggle to remove 'B' from the country.

Iain Duncan Smith, the former Conservative Party leader, told the Telegraph: 'How ridiculous. It is completely mad. We have a legal system that has lost all common sense.

'When we leave the European Union we can introduce our own bill of rights and then we can kick people like him out.'

A Home Office spokesman told the Sun on Sunday: 'Our priority will always be the safety and protection of the British public and we are extremely disappointed with SIAC's judgment, particularly as they have twice ruled this individual to be of national security concern.'