Lawyers for radical cleric Abu Hamza are asking the High Court for time to carry out further medical tests as he renews his long-running legal battle to halt his extradition from the UK to the US.
The lawyers plan to seek a temporary injunction pending a request for an MRI scan to be carried out due to his "deteriorating health".
In papers before two judges in London, Hamza's QC, Alun Jones, argues that there is "uncontradicted medical opinion that a scan is medically necessary".
Mr Jones adds: "If the applicant (Hamza) is unfit to plead, or arguably so, it will be argued that it would be oppressive to extradite him within the meaning of Section 91 of the 2003 Extradition Act."
The QC says a judge referred to Hamza's "very poor health" at an extradition hearing in 2008.
"Over four years later, it appears there has been, or may have been, a further deterioration, perhaps attributable to sleep deprivation and the continued confinement of the appellant in an unrelentingly harsh environment. The responsibility of the (Home Secretary) is a relevant factor here."
Hamza is fighting extradition to the US on terrorism charges along with other terror suspects.
Mr Jones says in his written submissions that, after further medical tests are carried out and considered by doctors on both sides, "there may be no issue", but at present "it cannot possibly be said there is no issue" and the medical tests should be carried out.
Magnetic resonance imaging (MRI) is a type of scan that is often used to diagnose health conditions which affect organs, tissue and bone. The QC is due to make his application for an injunction in open court before Sir John Thomas, President of the Queen's Bench Division, and Mr Justice Ouseley over the next couple of days.
He argues that the law is clear - "if a person is established to be unfit to plead, he should not be extradited". But if there is "an issue" as to his fitness to plead, "he should indeed be extradited" as the court of trial was the appropriate court to decide the issue.