Mladic stays in hospital after falling ill

Mladic is on trial for genocide, war crimes and crimes against humanity for his role in Bosnia's 1992-1995 war. (AAP)

Mladic is on trial for genocide, war crimes and crimes against humanity for his role in Bosnia's 1992-1995 war. (AAP)

Ratko Mladic remains in hospital after suddenly falling ill during his trial at the Yugoslav war crimes tribunal.

Former Bosnian Serb army chief Ratko Mladic will spend two days in hospital after suddenly falling ill during his trial at the Yugoslav war crimes tribunal, his lawyer says.

"He is still in the hospital. He will be there today and tomorrow," Branko Lukic said on Thursday.

"He is better (than) when he collapsed in the courtroom," he added, saying Mladic was able to communicate and had regained movement in his right arm and leg after suffering paralysis earlier in the day.

Earlier, Lukic had said his 70-year-old client was in "bad shape" and could not stand, communicate or open his eyes.

Mladic is on trial for genocide, war crimes and crimes against humanity for his role in Bosnia's 1992-1995 war.

Prosecution witness David Harland, a UN political adviser during the war, was giving evidence on Thursday when judge Alphons Orie noticed something was amiss with Mladic and suspended the hearing.

"Mladic was feeling unwell and he was taken to a hospital as a precautionary measure," said Nerma Jelacic, a spokeswoman for the International Criminal Tribunal for the former Yugoslavia (ICTY).

The man known as the Butcher of Bosnia has complained before of health issues, with his lawyer saying Mladic has suffered three strokes and a heart attack in the past.

He suffers from kidney stones, and last year was also treated for pneumonia.

Groups representing families of victims of the 1995 Srebrenica massacre, the worst atrocity on European soil since World War II, have in the past voiced concern over Mladic's health, saying they were afraid he might die before his trial was concluded.

The trial had resumed on Monday after being abruptly suspended because of prosecution irregularities on May 17, only a day after it opened in The Hague.

Mladic faces charges relating to the massacre in Srebrenica, as well as the terrorising of the Bosnian capital Sarajevo during 44 months of shelling and sniper fire which killed 10,000 people.

AF