America's fury as Hamza smuggles hate messages to Bin Laden's No 2... From UK jail cell

American counter-terrorism chiefs are demanding a full explanation from Britain of how radical cleric Abu Hamza was able to smuggle murderous messages from his UK prison cell to Al Qaeda's deputy leader.

The major diplomatic row comes in the wake of a long-running battle by US prosecutors to extradite the former imam of London's Finsbury Park mosque to stand trial in America.

Hook-handed Hamza was jailed for seven years in Britain in 2006 for inciting murder and racial hatred and is held at Belmarsh prison, South-East London, supposedly one of Britain's most secure jails.

But according to senior American intelligence sources, Hamza evaded the extensive security measures surrounding him to send a series of questions to Ayman al-Zawahiri, Osama Bin Laden's right-hand man.

Al-Zawahiri is believed to be hiding with Bin Laden in the lawless mountain region along the Pakistan-Afghanistan border.

Late last year, Al-Zawahiri - who has a £13million bounty on his head - posted a message on an extremist website run by Al Qaeda saying he would answer questions on any topic.

US intelligence tracked all the email replies and among them were messages from Abu Hamza. It is understood they were sent from an email address known to be linked to the cleric.

The sources say they have no doubt that al-Zawahiri was personally involved in answering the questions and that those posed by Hamza had genuinely originated from him.

US prosecutors have been fighting for four years to send Hamza for trial in the US. They accuse him of involvement in a global conspiracy to wage jihad against the US and other Western countries.

Among the most serious accusations is one that he was involved in the kidnap by Islamic radicals of 16 tourists in the Yemen in 1998. Four hostages, including three Britons, died in a rescue attempt.

Earlier this month the High Court turned down Hamza's latest appeal against efforts to send him to the US but his lawyers could still fight his extradition by applying to the House of Lords and the European Court.

For the Americans, frustrated by the length of time it has taken to bring Hamza for trial in the US, the revelation that he was also able to keep in touch with Al Qaeda's high command has caused widespread anger.

One source pointedly said that 'if he is transferred to US custody, he would be kept in the country's highest security prison in Colorado'.

Once there, the source added: 'It would be absolutely impossible for him to communicate with Al Qaeda.'

Hamza communicated with Al-Zawahiri, 'Osama Bin Laden's 'number 2 man', and questioned him over Al Qaeda's influence in Egypt

US counter-intelligence chiefs are said to be particular concerned because Hamza's questions suggest Al Qaeda may be planning a new front in its activities in Egypt - where both Hamza and al-Zawahiri were born - and openly discuss the murder of police and other law enforcement officers.

Hamza wrote: 'I have two questions for you, our great Shaykh.

'First: When will there be a wing of the organisation in Egypt? And if it is there, how can one join the caravan?

'Second: What is your opinion of the officers of State Security in Egypt? Are they committing unbelief? And is it permissible to kill them? Or does the matter have its particulars?'

Al-Zawahiri answered: 'First, the days will reveal to you what you didn't know. And news will come to you from those who didn't have it.

'Second, I believe the officers of the State Security Anti-Religious Activities Branch and who investigate Islamic causes and torture the Muslims are infidels, each and every one of them.

'They know more about the Islamic movements than many of those movements' members know about them.

'And it is permissible to kill the officers of State Security and the rest of the personnel of the police, whether we declare them unbeliever individually or declare them unbelievers in general, if that is the framework of a combat campaign.

'As for the discretion of your brothers in Qaeda al-Jihad Group, it is to focus at this stage on striking American and Zionist targets and targets of the states allied with it in the aggression against the Muslims and on serious efforts to change the regimes in the hire of the Crusaders and Jews. And Allah knows best.'

Last night a Whitehall source said: 'If the Americans had information that a terror suspect in Britain was in communication with senior figures in Al Qaeda, I am confident we would be informed.'