The Crown Prosecution Service (CPS) has defended itself after it was accused of preventing police acting sooner against Muslim preacher Abu Hamza al-Masri.
Abu Hamza was found guilty of 11 out of 15 charges
Earlier, anti-terror police said evidence against the cleric was sent to prosecutors "on several occasions" since 1999 but no action was taken.
But the CPS says there was "insufficient evidence" to act sooner.
Abu Hamza, 47, from London was jailed on Tuesday for seven years for inciting murder and racial hatred.
Detectives say they were "very alert" to Abu Hamza's activities.
UK police had interviewed Abu Hamza during 1999 over alleged involvement in terror plots in Yemen, but no charges were brought.
ABU HAMZA VERDICTS
Guilty of 6 charges of soliciting to murder
Guilty of 3 charges related to "stirring up racial hatred"
Guilty of 1 charge of owning recordings related to "stirring up racial hatred"
Guilty of 1 charge of possessing "terrorist encyclopaedia"
Not guilty of 3 charges of soliciting to murder
Not guilty of 1 charge related to "stirring up racial hatred"
He was eventually arrested in 2004 following an extradition request from the US, but charged five months later with offences relating to his activities in the UK.
Cassettes and videos of speeches made by Abu Hamza formed the basis of the case against him.
A CPS spokesman said evidence presented before the end of 2003 - relating to different investigations to the Old Bailey race hate trial - was found to be "insufficient to prosecute".
"The first tape in relation to this matter [the Old Bailey trial] came to us at the end of 2003 and the majority of tapes submitted for the prosecution came after the searches in May 2004 when they were seized."
A senior French intelligence chief has reportedly said that his country passed on evidence that Abu Hamza sent dozens of people from Finsbury Park Mosque to terror training camps in Afghanistan.
French intelligence believed Abu Hamza was playing a key role in jihad, Christophe Chaboud, director of France's national anti-terrorism co-ordination unit (UCLAT), told the Guardian.
"We thought it would have been necessary to take action, to arrest and prosecute him," he added.
Former anti-terrorism officer Charles Shoebridge said he thought no action was taken against Abu Hamza for so long because the authorities had a "misplaced fear of alienating mainstream Muslim opinion".
Abu Hamza was imam at the Finsbury Park mosque
"The more you look... the more you come to the uncomfortable conclusion that not operational reasons or evidential reasons or legal reasons come to the fore when you look at the decisions not to take action against people like Abu Hamza, but more political reasons," he told BBC News.
On Tuesday, Abu Hamza was convicted of inciting murder and racial hatred and possession of a terrorist document.
The preacher could still face extradition to the US on terrorism charges when he is released from jail in Britain.
He was convicted of 11 of the 15 charges he faced and will remain at Belmarsh high security prison, where he has been held since his arrest in 2004.
It is understood he will be eligible for parole in 2008.
Meanwhile, Scotland Yard has denied newspaper reports linking the preacher to the four British-born Muslims who killed 52 people when they bombed London's transport network on 7 July last year.
A spokesman said: "We have no evidence at this stage that any of those involved had connections with Abu Hamza."