Dec 15, 2006
The court instructed the provincial governor not to sign the bill, which is opposed by President Pervez Musharraf.
North West Frontier Province, which is governed by an alliance of religious parties sympathetic to the Taleban, passed the legislation last month.
Last year a similar bill was declared unconstitutional by the Supreme Court.
President Musharraf, who says he wants Pakistan to espouse an enlightened, moderate form of Islam, has denounced the bill as fundamental breach of human rights.
Correspondents say it is almost unheard of for the same bill passed by a provincial assembly to be challenged twice in the courts by the federal government.
The Supreme Court ordered the NWFP governor not to sign the Hisba (Accountability) bill into law until the case had been decided.
It said it would take up the matter again in the third week of January, when the NWFP government is to be given a chance to defend the bill.
The ruling came after a petition from President Musharraf, Attorney General Makhdoom Ali Khan said.
NWFP Information Minister Asif Iqbal Daudzai, a member of the ruling alliance of religious parties, accused the government of being undemocratic.
"We are really surprised. We drafted the bill in light of the Supreme Court's directives," he told Reuters news agency.
"The federal government's decision to go to the court exposes their claims that they believe in democracy."
The bill adopted by the NWFP assembly last month was a watered-down version of the legislation rejected by the Supreme Court last year, again after a petition from the president.
The key difference between the bills is that the proposed department to be set up to enforce morality will not have its own police force.
But it would, however, be able to requisition police "to promote virtue and prevent vice".
The plan is reminiscent of the infamous Department for the Prevention of Vice and Promotion of Virtue, set up by Afghanistan's former Taleban rulers.
It became a focus of criticism by human rights organisations.
Religious police would patrol the streets in Afghanistan, forcing women to adhere to a strict dress code and men to pray and grow their beards, among other things.
Observers say the battle in the courts reflects a struggle between moderates and conservatives over the direction of Pakistan.
Two of the country's four provinces are governed by the six-party Islamic alliance, the Muttahida Majlis-e Amal (MMA).
The BBC's Barbara Plett in Islamabad says President Musharraf has had a tacit alliance with the Islamic parties but he has become increasingly critical of them.
His recent support for amendments to hardline Islamic laws on rape despite their strenuous objections prompted some analysts to think he might keep quiet about the Hisba bill as a trade-off.
The fact that he has not, our correspondent says, will only fuel speculation that he is seeking to replace the Islamists with more moderate allies.