Iran's parliament has bowed to widespread opposition and postponed voting on a bill that would allow men to take additional wives without the consent of their first wife.

Polygamy is not practised in mainstream Iranian society.

But the government of President Mahmoud Ahmadinejad has pursued amendments to a landmark women's rights bill that would allow multiple marriages.

It's part of a move to enshrine elements of Islamic law in Iran's legal system.

However, the proposal has raised so much ire from women's rights groups and the judiciary that a planned vote on the bill this week had to be postponed.

Rights groups say the postponement is a significant victory for women, but hardliners, including some conservative female legislators, say they won't give up the fight to bring the amendments to a vote.

Another government amendment that drew objections from the judiciary is an article that would introduce a tax on the money grooms pay to wives upon marriage under Islamic law. Opponents say the government should not be allowed to get its hands on that money.

The Family Protection Bill was drawn up by the judiciary with the intention of allowing women to serve as judges for the first time since the 1979 Islamic revolution.

As initially drawn up, it would also impose prison sentences for men who marry girls before they have reached legal age.

Under Iran's Islamic law, a man can have up to four wives with the consent of his first wife or wives. But the practice is frowned upon by most Iranians.

Earlier this week, dozens of women's rights activists, including Nobel laureate Shirin Ebadi, went to parliament to protest the bill. Judiciary chief Ayatollah Mahmoud Hashemi Shahroudi also blasted the government's amendments, saying they were harmful to women.

Shahroudi said the amendments have overshadowed the pro-family articles in the bill drawn up by the judiciary.

"The dowry tax was unnecessary. It is harmful to women ... (the other part) should be amended and debated away from controversy," he told judges Monday.

"That the parliament postponed the vote is a significant victory for women in Iran," said women's rights activist Farzaneh Ebrahimzadeh. "But we have to fight on. The bill may return to the parliament for a vote but we have to make sure that articles reducing the rights of women are deleted."

Fatemeh Alia, who supports the multi-marriage law, said in remarks published Thursday that she and other conservative legislators won't give in and will fight for a vote in parliament soon.

"Lawmakers will never give up drawing up Islamic laws ... and won't give in to mud slinging by a group of secularists gathered around those obtaining gifts from aliens," Alia was quoted as saying by the newspaper Etemad-e-Melli. She was referring to Ebadi, who received the Noble Peace Prize in 2003.

Iran has refused to ratify the UN convention on women's rights, and the country's senior clerics in Qom, Iran's main centre of Islamic learning, have rejected the convention as un-Islamic.

Under the strict form of Islamic law practised in Iran, a woman needs her husband's permission to work or travel abroad. And a man's court testimony is considered twice as important as a woman's.

In September 2006, Iranian activists launched a campaign to try to change laws that deny women equal rights in matters such as divorce and court testimony.

But despite being shut out of the country's highest political posts, Iran's 35 million women have greater freedoms and political rights than women in most neighbouring Arab states, including the right to vote and hold public office.

Those freedoms got a boost with the 1997 election of former president Mohammad Khatami, a reformist who appointed a female vice-president.

Since then, other women have held positions within the government but have not been cabinet ministers. And while women in Iran can run for parliament, they're prohibited from running for president.