Pakistani lawmakers passed a resolution Monday urging that the president sign a regulation that imposes Islamic rule in a northwestern valley in exchange for peace with the Taliban.

Meanwhile, authorities announced the arrest of a fifth suspect in the deadly siege of the Indian city of Mumbai last year.

Hours after a Taliban spokesman said lawmakers would be considered to have abandoned Islam if they opposed the Islamic law deal, the National Assembly unanimously approved the resolution aimed at President Asif Ali Zardari — though at least one party boycotted.

The provincial government in northwestern Pakistan agreed in February to impose Islamic law in the Swat Valley and surrounding areas in exchange for a cease-fire with the local Taliban.

Western and Pakistani critics say the agreement represents a dangerous surrender to extremists behind a campaign of terrorism in the Swat Valley and more broadly across the border region with Afghanistan. Amid the criticism, Zardari has delayed signing the agreement.

His stance has long been that he won't sign until peace is achieved in the area — but he hasn't defined what that means. The delay led a hardline cleric mediating the agreement to leave Swat in anger last week while also upsetting lawmakers from the region.

Over the weekend, the federal government said Zardari wanted opinions from members of Parliament first.

"The whole nation is united in its support of the Swat regulation and wants the president to approve it," Prime Minister Yousuf Raza Gilani said at the start of a floor debate on the pact Monday.

Gilani said he was present at meetings with Zardari and the local government "where the president gave the consent that you should go ahead and you should have (the) deal."

Even without the president's approval, judges trained in Islamic law have already began hearing cases in Swat, and witnesses say the Taliban are in effective control of much of the region. Supporters say the changes in the legal system will speed up justice there, not lead to harsh punishments or restrict the rights of women.

Zahid Khan, information secretary for the Awami National Party, which leads the provincial government and has been repeatedly targeted by extremists, warned earlier that it will review its alliance with Zardari's party if the delays continue.

The Awami National Party notes that an Islamic legal system has long been a local demand in Swat, and says it is the best hope for ending the bloodshed.

"We are not against taking up the issue in Parliament, but this is not constitutionally needed," Zahid Khan said. "The president has the power to do it on his own, and he must do it to avoid any worsening of situation in Swat."

In a sign that Zardari was searching for political cover to avoid backing the deal, a top member of his party on Monday accused the Taliban of failing to hold up their end of the bargain.

Those brokering the deal have given few specifics about conditions placed on the Taliban.

But Pakistan People's Party information secretary Fauzia Wahab said the Taliban were supposed to cooperate with security forces, denounce suicide attacks, close their training camps and turn over their weapons, among other measures.

"The agreement was two-way, it was not one-way," she said.

Muslim Khan, the Taliban spokesman, did not say whether the Taliban would punish legislators opposing the deal other than to say a militant council would discuss the matter. The charge of apostasy, or abandoning Islam, carries the death penalty in some quarters.

Lawmakers from the Muttahida Quami Movement, a party based in the southern city of Karachi that has a strong anti-Taliban stance, walked out of the session. "We can't accept Islamic law at gunpoint," said Faroog Sattar, a top party leader.

Under tremendous international pressure, Pakistan has acknowledged that part of the conspiracy behind November's siege of Mumbai was hatched on its soil. The attack left 164 people dead, along with nine of 10 gunmen.

Pakistani Interior Ministry chief Rehman Malik said late Monday authorities had arrested another suspect, and were still searching for four more of nine alleged perpetrators.

Shahid Jamil Riaz was arrested in Karachi, Malik said. He stands accused of maintaining financial accounts and helping plan the attack, alleged to have been masterminded by operatives of the banned Pakistani militant group Lashkar-e-Taiba.

Malik further pressed India to give more information to aid in Pakistan's investigation. He said two DNA reports that India had handed over on separate suspects were identical, indicating a mix-up.

Also Monday, visiting Sen. John Kerry met with Zardari, Gilani and other top officials, including Lt. Gen. Ahmed Shujaa Pasha, the head of Pakistan's most powerful spy service, Inter-Services Intelligence.

Kerry, chairman of the Senate Foreign Relations Committee, is spearheading a bill to triple nonmilitary aid to Pakistan to $1.5 billion a year for 10 years.

The goal is to help Pakistan improve economic, educational, and other sectors partly to lessen the allure of militancy.

In a statement after meeting Kerry, Gilani urged the U.S. not to attach conditions to the aid funding.

During a news conference, the senator largely sidestepped piercing questions about U.S. drone strikes on militant targets in Pakistan's northwest, saying he would convey Pakistani dismay over the escalated missile campaign to his colleagues in Washington.

Kerry also took a diplomatic stance when asked about U.S. allegations that Pakistan's spy agencies are assisting the Taliban and linked groups in Afghanistan.

"I think that he and your government are making enormous efforts to guarantee the absolute cooperation and accountability of the intelligence efforts in this country," Kerry said.