Lawmakers on Wednesday overwhelmingly approved a bill introduced by the government of military ruler President Pervez Musharraf that will overhaul widely-criticised religious legislation dating back to 1979.
At present the laws say that women must produce four Muslim male witnesses as evidence of rape -- an almost impossible burden of evidence -- or potentially face adultery charges themselves.
"We will protest countrywide against the bill and the policies of the military dictator," said Liaquat Baloch, deputy leader of the MMA (Muttahida Majlis-e-Amal, United Action Front), an alliance of key Islamic parties.
"This bill has been brought under the directions of the United States and implemented by their representative in Pakistan, General Musharraf," Baloch told AFP.
The Pakistani government had backed out of three previous attempts to push the bill through following an outcry from religious hardliners in this conservative Islamic republic.
It was a largely symbolic victory as the number of women actually convicted under the notorious "Hudood (Limits) Laws" is relatively small. The laws run parallel to Pakistan's British-influenced penal code.
But the issue has reopened faultlines between Musharraf, a self proclaimed "enlightened moderate", and the religious parties who bitterly opposed his support for the US-led invasion of Afghanistan in 2001.
"Women will no longer suffer victimisation because the clause related to rape and adultery has now been put under the (secular) Pakistan penal code," Musharraf said in a televised address to the nation late Wednesday.
"We will continue to make efforts to make sure that there is no discrimination against women."
Musharraf -- who seized power in a 1999 coup and once counted the religious parties as his allies -- has escaped at least three assassination attempts blamed on Islamic extremists.
Bearded and turbaned hardline legislators stormed out of the national assembly, the lower house of Pakistan's parliament, before the vote took place on Wednesday.
Opposition leader and MMA secretary general Maulana Fazlur Rehman gave a fiery speech to lawmakers on Wednesday in which he warned that the bill would "turn Pakistan into a free-sex society."
The late military dictator General Ziaul Haq introduced the Hudood Laws 27 years ago as part of a sweeping Islamisation of Pakistan that coincided with the country's role in the anti-Soviet "jihad" in Afghanistan.
The maximum sentence for adultery by a man or a woman under the laws is death by stoning, although that has never been enforced and those convicted of the crime get jail or a fine instead.
Human rights groups who have long campaigned for a change in the law hailed the bill as a step forward for Pakistani women.
Islamist groups have vowed large scale protests after Pakistan's  amended laws to transfer rape cases from Sharia courts to .

Sharia courts in Pakistan, based on Islamic religious law, try rape cases under "''''" laws instituted in 1979. The laws say that a rape victim must herself face  charges unless she can produce four Muslim male witnesses to the rape. The maximum sentence for adultery is death by .

The laws are widely condemned by women's rights groups as an almost impossible burden of proof. Human rights groups have long campaigned for changes to the religious laws. On Wednesday, Parliament voted overwhelmingly in favor of the amendments.

A coalition of Islamic parties, the  (MMA), which forms the Parliamentary opposition, has opposed the changes, saying it encourages "free sex". The MMA says that its members will resign from national and provincial assemblies in protest.