Both men must serve a minimum of 35 years in prison

Yusuf Abdillh Jamma, 20, of London, and Muzzaker Imtiaz Shah, 25, of Birmingham, were sentenced to life in prison following the shooting in 2005.

Both are understood to have been questioned over an attack on an inmate at Frankland Jail in County Durham.

The prisoner was reported to have been stabbed in the stomach on 6 March.

Statements taken

Police said the 22-year-old inmate who was attacked was also serving a life sentence for murder.

A Durham Police spokesman said: "Statements have already been taken from members of staff.

"A file will be prepared for submission to the Crown Prosecution Service and they will decide what action to take, if any.

"The victim was taken under armed police escort to Durham's University Hospital and was returned to the jail after treatment for stab wounds to the stomach and cuts to the face."

Following a trial last year, Shah and Jamma were both told they must serve a minimum of 35 years in prison before being considered for release.