The jury trying the mother of Shannon Matthews was told it will not sit today as her co-accused is continuing to receive medical treatment following an attack in prison.
Michael Donovan, 40, of Lidgate Gardens, Batley Carr, was attacked in prison on Thursday evening, Leeds Crown Court heard today.
Donovan and Shannon's mother, Karen Matthews, 33, deny kidnapping and falsely imprisoning Shannon, who was nine when she went missing from her home in Dewsbury, West Yorkshire, in February.
They also deny perverting the course of justice.
Last week the court heard the prosecution describe how Shannon was kept locked up and drugged in Donovan's flat for 24 days.
The prosecution case is that Matthews and Donovan planned the kidnap of Shannon, who is now 10, to claim £50,000 of reward money.
Today the judge, Mr Justice McCombe, told the jury: "Last Friday, before you came into court, I was informed that on the previous evening Mr Donovan has been assaulted at Leeds Prison by another inmate.
"As a result he sustained facial injuries.
"Mr Donovan still requires some medical attention and his counsel has asked that we do not sit today for that to be obtained."
The judge warned the jury not to draw any conclusions from this course of events.
He added: "It's sometimes what happens in prison, regrettably."
The case was adjourned until tomorrow.