"It was a violent physical incident involving another inmate but I do not know whether a weapon was used. There is no information on whether he received treatment," said Abu Mussa, a spokesman for the former head of London's Finsbury Park mosque, was quoted as saying in The Sun daily.
"There are some tasty characters in there. They don't care about getting caught and one of them wanted to show Hamza exactly what they think of him," he added.
Belmarsh prison in the capital holds some of the most dangerous prisoners in Britain.
According to the spokesman, the former imam "had previously received threats from other prisoners on the lines of 'we are going to kill you'".
Mussa said a complaint would be handed over to the prison authorities.
Hamza, 47, a distinctive figure with one eye and a hooked hand, was charged in October with 10 counts of soliciting murder.
The little-used charge, covered by an 1861 criminal law, relates to inciting others to murder unspecified people and carries a maximum sentence of life imprisonment.
In Hamza's case it is connected to alleged incitement by the cleric at public gatherings to kill non-Muslims, specifically Jews, according to four of the charges.
He was also charged with four counts of using threatening, abusive or insulting behaviour with intent to stir up racial hatred; one count of possessing threatening, abusive or insulting sound recordings; and one count of possessing a terrorist document.
Hamza is sought for extradition by the United States on separate charges, with this process suspended until the British court case is completed.
Between Mr. Abubu here and Mullah Omar (I know you're keeping an eye out for him, dead), we could have one complete radical Muslim cleric.
If the mystery man used Hazmat's own hook in the attack, I'll throw into the kitty.
"tasty characters"
Now, THAT is funny!!!!