Unmarried Australians holidaying in Bali could find themselves jailed for having sex, under strict new laws.

The warning comes as Indonesia, the world’s most populous Muslim country, gears up to pass new laws making consensual sex between unmarried adults a crime, and also making it illegal for unmarried couples to live together.

The move has angered civil rights groups and legal observers, with one Australian Indonesian law professor describing the imminent legislative change “extremely regressive”.

On Friday, Australia updated its travel advice for Indonesia, warning tourists could soon be charged for having sex outside marriage.

“A large number of laws may change and these will also apply to foreign residents and visitors, including tourists,” the Department of Foreign Affairs posted to the Smart Traveller website on Friday.

The changes are part of sweeping update of Indonesia’s penal code introduced in 1995, and are expected to become law by the end of September.

Indonesian politicians have told Reuters that the new penal code, which will replace a Dutch colonial-era set of laws, is a long overdue expression of Indonesian independence and religiosity.

There has been a recent trend towards deeper religious piety and conservative Islamic activism across the nation.

Balinese bathe during Banyu Pinaruh, a cleansing ritual, at Keramas in Gianyar on Indonesia’s resort island of Bali. Photo: AAP

Under the proposed laws, unmarried couples who “live together as a husband and wife” could be jailed for six months or face a maximum fine of 10 million rupiah ($1040) – which is three months’ salary for many Indonesians.

A recent study also found up to 40 per cent of Indonesian adolescents engaged in pre-marital sexual activity.

According to Nine newspapers, other changes listed in the proposed bill include making it illegal to criticise the president (a law struck down by Indonesia’s Constitutional Court in 2006), spread communist ideology, making it illegal for couples who aren’t married to live together, banning the display of contraception to a minor, curbing access to abortion and criminalising fake news, bestiality and black magic.

DFAT says Indonesia is the No.2 destination for outbound Australian tourists, with more than one million Australians visiting our northern neighbour every year.

Director of the University of Melbourne’s Centre for Indonesian Law, Islam and Society, Tim Lindsay, told Reuters: 
“Across the board, this is a ratcheting up of conservatism”

“It’s extremely regressive,” he said.

Indonesian law-maker Teuku Taufiqulhadi was questioned on the new laws applying to foreigners.

When asked whether tourists in Indonesia could face jail for extramarital sex, Mr Taufiqulhadi replied: “No problem, as long as people don’t know”.

-with agencies