Rights groups urged the Indonesian government on Tuesday to block a proposed law banning women from sitting astride motorcycles in deeply Islamic Aceh province, where the position is deemed "improper".

The mayor of Lhokseumawe city in Aceh, where Shariah, or Islamic law, is enforced, circulated a letter on Monday explaining that the obligation for women to sit sidesaddle was "to avoid immoral acts".

Women ride on the back of motorcycles at a university in Banda Aceh, the capital of Aceh province, Indonesia, on Tuesday. Rights groups urged the government to block a proposed law banning women from sitting astride motorcycles. [Photo/Agencies]

"Adult women who are riding on the back of a motorbike cannot straddle unless in an emergency," Mayor Suaidi Yahya's letter read, adding that the ban included female drivers straddling.

The official said last week that women sitting astride motorcycles would "provoke the male driver" and that it would be against Islamic law.

The letter also proposed banning men and women from hugging and holding hands while on vehicles, and banning tight or scanty clothing in public.

The move comes after leaders from Aceh, the country's only province ruled by strict Shariah law, drafted a series of new bills, including banning women from wearing tight trousers, stoning adulterers and flogging gay people.

Local women's rights activists have rejected the proposed ban "because it completely ignores the driving safety principles", said Roslina Rasyid, of the Indonesian Women's Association for Justice, a legal aid group in Lhokseumawe.

"Sitting astride guarantees better safety, and I'm sure most people can only sidesaddle for 15 minutes. What if the person is overweight and causes an imbalance? It could cause an accident," she added.

Nurjanah Ismail, a lecturer on gender issues at the Ar Raniry Islamic Institute in Aceh's capital, Banda Aceh, criticized the proposed law.

"There is no need to question this practice, let alone regulate it, because people do it for safety," she said. "Women sitting in that way cannot be considered bad or in violation of Shariah. Islam is beautiful, so do not make it difficult."

Andy Yentriyani, a National Commission on Violence Against Women activist, said the policy was "part of policies that discriminate against women in this country in the name of religion and morality".

The central government said it could not review the ban because it was not yet formalized as a bylaw and did not include punishments. Local media reported the interior minister as saying he would review the bylaw if it passed.

But the ministry's regional autonomy director-general, Djohermansyah Djohan, who would oversee any revision, said, "We'll just leave it to the people of Aceh to decide whether to accept it or not."

AFP-AP