Judges at the Yugoslav war crimes tribunal on Wednesday ordered a full medical checkup of ailing genocide suspect Ratko Mladic after he said he was too ill to attend a hearing last week.

A complete picture of the 69-year-old former Bosnian Serb military chief's health will help "better assess whether and to what extent his health condition could affect the preparation of the upcoming trial," judges said in a written order.

The order comes amid a slew of health complaints from Mladic since he arrived at the UN court's detention unit in May following his arrest in Serbia after 16 years on the run.

Mladic has been suffering the effects of a kidney stone, had surgery for a hernia, and has been hospitalised with pneumonia. His lawyers and family also say he suffered two strokes during his years as a fugitive.

Independently of the court-ordered checkup, a team of Serbian doctors chosen by Mladic is visiting him this week to assess his health.

The wartime commander of the Bosnian Serb army faces 11 charges including genocide, persecution and extermination for allegedly orchestrating atrocities committed by his forces throughout the 1992-95 Bosnian War. Judges entered not guilty pleas on his behalf after he refused to plead.

Mladic is not the first senior Serb to suffer ill health in tribunal custody. Former Yugoslav President Slobodan Milosevic died of a heart attack in his cell in 2006, forcing a premature end to his genocide case. Milosevic's trial had dragged on for nearly four years, due to a combination of his health problems and his political grandstanding in court.