Anwar is being held under the Internal Security Act which allows for indefinite detention without trial. The former finance minister was led into the court room with a swollen left eye and bruises on his right arm but he looked cheerful, a reporter said.

Seven charges -- four on unnatural sex and three on corruption -- were read out against Anwar but he pleaded not guilty to all the charges.

The Bernama news agency earlier said he was to face five charges of corruption and five of unnatural sex acts. If convicted of corruption, Anwar faces a maximum of 20 years jail or a fine of 5,263 dollars or both. If unnatural sex is proved he could go to jail for 20 years or be caned under the penal code, officials said.

Some 200 riot police and scores of plain clothes officers were stationed outside thecourthouse and several roads leading to the area were sealed, witnesses said.

Anwar, Prime Minister Mahathir Mohamad's former protege and anointed heir was sacked from the Cabinet on September 2 due to his ``low morals''. He has denied all charges and claimed there was a ``high-level conspiracy'' to oust him.