Pakistani security forces were on their highest state of alert on Sunday, the day before critical parliamentary polls, after a suicide bomber killed 47 people at an opposition election rally.
The blast heightened the tension surrounding Monday's vote, with violence and allegations of rigging blighting the run-up to an election that could drastically weaken the grip on power of President Pervez Musharraf – a key ally in the US-led "war on terror."
Authorities clamped a curfew and called in troops to the northwestern tribal town of Parachinar, bordering Afghanistan, after Saturday's suicide car bomb targeting supporters of slain opposition leader Benazir Bhutto.
"Since there is a curfew voting will not be possible. It is likely that the election in the Parachinar constituency may be postponed," senior local administration official Fida Mohammad Khan said.
He added that the death toll, the deadliest in Pakistan since Bhutto's assassination at a political rally in December, had risen to 47 with 110 wounded.
The government says it has deployed 500,000 security personnel for the vote, including 81,000 troops, and it pledged Sunday that voting would be peaceful and fair.
"The elections will be free, fair, transparent and peaceful. We will not let anyone succeed in disrupting the election process," Information Minister Nisar Memon told reporters in Islamabad.
He warned of a crackdown on any protests after polling day.
"If anyone wants to create disturbance after elections we have security arrangements to deal with them sternly," Memon said.
But Bhutto's widower, Asif Ali Zardari, said in an interview with Britain's Sunday Times newspaper that he would have "no choice" but to call supporters onto the streets if the polls were rigged.
"My wife has been killed, yet I've calmed people down, stopped them protesting, I've called no strike. But I'm telling you, people are absolutely on the warpath," the paper quoted him as saying.
"If the elections are rigged the situation will go out of my hands. We'll have no choice but to take to the streets."
Pakistan's election commission promised free polls.
"Everything has been put in place to make these elections the most transparent and fair in the history of Pakistan," said commission secretary Kanwar Dilshad."
Interior Ministry spokesman Brigadier Javed Cheema told AFP that attempts to disrupt the polls would fail.
"Security forces are on highest alert for the smooth and peaceful conduct of the polls," Cheema said. "Polling stations will be fully secured, the security of the voters will be ensured at all costs."
In fresh violence on Sunday, four paramilitary soldiers were killed when a roadside bomb hit their vehicle in the southwestern province of Baluchistan, officials said.
Separately a high school was badly damaged by a bomb blast in the tribal district of North Waziristan on Sunday, an administration official said. There were no casualties.
A resident of Parachinar, Khalil Shah, said Sunday that gunfire was continuing in the town after Saturday's blast. Some areas were very tense, especially where Sunni and Shiite communities live together, he said.
Attacks in the run-up to the elections have killed nearly 150 people, while the claims of rigging in favour of Musharraf's allies have also helped destabilise the nuclear-armed nation.
Musharraf, who sacked several key judges last year to pave the way for a second presidential term, faces impeachment if the opposition wins more than two-thirds of parliament.
The White House, which counts Musharraf as a bulwark against Al-Qaeda and Taliban militants, called for people to make their views known through the ballot, not the bomb.
"We want to see an election in which all the parties can compete fairly. Violence is not the answer and we know this latest attack will not stop the people of Pakistan from voting," White House spokesman Gordon Johndroe said. (AFP)
Pakistan on alert after suicide carnage