President Habibie, who has promised sweeping democratic reforms since he succeeded former president Suharto, said: "I ask the armed forces to disclose the truth about rumours that at several locations, riots and looting was organised by certain groups who incited many people to burn and loot."
Mr Habibie did not say who might have been responsible, but - significantly - he added that the armed forces needed to take action against any of its members who had fallen short of the military's usual "high standards".
Indonesia's National Human Rights Commission has said it has received accounts from witnesses that say that organised groups - believed to be linked to pro-Suharto elements in the army - whipped up much of the violence.
At the same time, other rights groups in the Indonesian capital, Jakarta, have started to document what they say was a campaign of assaults, gang rapes and killings directed against members of Indonesia's prominent but unpopular ethnic Chinese community. A report in the New York Times cited a worker at a women's aid centre in Jakarta saying she believed hundreds of women were still being treated at hospitals for wounds inflicted during the disturbances, which culminated in the overthrow of President Suharto.
The newspaper said aid workers feared that most of the women were too traumatised and too frightened of reprisals to report their experience to officials, and that some had even committed suicide.
Because of the organised nature of the attacks, the newspaper said, aid workers suspect the hand of the armed forces.
Eighteen police officers are facing charges in the shooting deaths of four student protesters on 21 May.
The leader of Indonesia's largest Muslim opposition bloc, Amien Rais, said he also believed certain groups were specifically encouraged to riot during May's political turmoil.
Indonesia's Chinese community has traditionally dominated the country's commerce and industry and has been made the scapegoat on several occasions for ordinary people's economic hardship.Reuse content