A father who was visiting his son inside the prison told Sky News the stabbing happened in one of the communal areas.
He told Sky’s Tom Parmenter: “I saw two ambulances going in and someone said a prisoner has stabbed someone.
“It’s just another day at Wandsworth jail – you do worry as a parent.
“It is chaotic right now – even the officers inside all say they need more staff, my son is always calling saying he is on a lockdown meaning they can’t leave their cells at all, not for a shower not for anything.
“It’s unacceptable, yes they have to be punished but it is inhumane.”
The stabbing comes days after Daniel Khalife, a 21-year-old terror suspect, went missing from the prison on Wednesday.
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