The new draft law is meant to modernise Indonesia's 1918 Criminal Code, which was last updated in 1958, but some of its proposals constitute a big step back to the Middle Ages.

In a country where many people earnestly believe that they could be killed, injured or robbed by a sorcerer using black magic, that crime will, for the first time, become part of the criminal law.

News portal Detik.com reported late on Thursday that people guilty of using black magic to cause "someone's illness, death, mental or physical suffering", face up to five years in jail or 300 million rupiah ($A31,000) in fines.

Even claiming to have the power to cast dark spells would become a criminal offence, and if the magic was performed for financial gain, the penalty would increase by one-third. "White" magic would remain legal.

Commentators quoted in the Jakarta Globe newspaper agreed it may be difficult to gather hard evidence for these offences.

The new criminal code, which was drafted by the country's Ministry of Justice and Human Rights and circulated this week to parliamentarians, is also informed by the growing sense of religious puritanism in Indonesia, and so takes a much stronger line on moral "offences". Indonesian law has long contained criminal sanctions against adultery, but in the new 500-page draft, the penalties are beefed up considerably – now those caught straying outside the marital bed may find themselves spending up to five years on a prison pallet.

Ministry spokesman Goncang Raharjo said the existing maximum penalty for adultery of nine months had failed to stop the practice, so "we increased the sanctions to prevent people from easily committing adultery".

Living together outside wedlock would also be criminalised for the first time, earning cohabiters up to one year in jail, and putting it on a par with prostitution.

All the provisions in the new law, including those related to the dark arts, were included for the good of the people, the ministry insisted. Khatibul Umam Wiranu, an MP from president Susilo Bambang Yudhoyono's Democrat Party, agreed with the new proposals when contacted by the Jakarta Globe, but said of witchcraft that charges should be "based on fact finding, not [just] on someone's statement".

As for adultery, it was "the beginning of many social problems", so the sentence "should deter offenders, [and] nine months is not long enough". Five years, however, was "too long", he said.

The law contains 766 articles across the gamut of criminal and immoral activity. But before becoming law, it must pass through the country's House of Representatives, where it could potentially pick up significant amendments.