Lindsay Murdoch, Jakarta – The Habibie Government is preparing to ban former president Soeharto from leaving Indonesia amid renewed calls for him to be investigated over a wave of extrajudicial killings in the 1980s.

The Justice Minister, Mr Muladi, said on Monday night his ministry was waiting for the travel ban request to come from the Attorney-General's office, which is examining how the Soeharto family built a multi-billion-dollar fortune during his 32-year rule.

A leading constitutional lawyer, Professor Ismail Suni, called on the Attorney-General's office to widen the investigation to include the killings of scores of alleged criminals in Jakarta.

In an early 1990s autobiography, Soeharto: My Thoughts, Sayings and Deeds, he admitted responsibility for the execution of organised criminal gangs roaming the city's streets. He justified the killings by saying the criminals "had acted beyond any sense of humanity". Bodies were left in the open as a warning to other criminals. Professor Suni said the Soeharto autobiography was "one piece of evidence of his criminal record".

But Professor Suni, an adviser to President Habibie, said Mr Habibie was exempt from questioning about his own relationship with Mr Soeharto. "By theory, he's a Soeharto crony, so he can be grilled also," Professor Suni said. "But not as long as he is still president. As president he only bows to the People's Consultative Assembly [Parliament]."

The Justice Ministry has already banned two of Mr Soeharto's sons, Mr Bambang Trihatmodjo and Mr Hutomo Mandala Putra, from leaving the country pending the outcome of inquiries into their business activities.