ISLAMABAD (Reuters) - A bomb blast killed around 40 worshippers attending Friday prayers at a mosque in a restive area of northwest Pakistan, a senior official in the area told Reuters.

Pakistan's Prime Minister Yusuf Raza Gilani (R) shake hands with U.S. special envoy Richard Holbrooke at the prime minister's residence in Islamabad June 5, 2009. REUTERS/Mian Khursheed

“The death toll is 40. We have no idea as yet how many have been wounded,” said Atif-ur-Rehman, the senior-most government administrator in the Upper Dir district, close to Swat Valley, where the army has been conducting a major offensive against the Taliban.

Umer Rehman, a resident of Hayagai village, around 200 km (125 miles) northwest of Islamabad, said 30 bodies had been identified.

“A large number of body parts are scattered in the mosque. We don’t know whether these are parts of the dead who have been identified or of others.”

Prime Minister Yusuf Raza Gilani said such incidents would not “deter the government from its resolve to eliminate this scourge (of terrorism) from the country.”

Earlier on Friday, police arrested suicide bombers in Islamabad and nearby Rawalpindi, Pakistan’s interior minister said.

U.S. special envoy Richard Holbrooke consulted the country’s leaders on what needs to be done once the army eliminates the Taliban in Swat valley.

Gilani urged the United States to write off Pakistan’s debt, which at end-March stood at $1.55 billion, and told Holbrooke America should expedite the supply of military hardware.

Interior Minister Rehman Malik told journalists the suspected bombers caught in Islamabad and Rawalpindi had suicide jackets, but did not say how many. The News daily reported four men were being held.

Roadblocks have multiplied in recent days in both the capital and Rawalpindi, where the army is headquartered, over fears of attacks in retaliation against the Swat offensive.

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The military says more than 1,200 militants and 90 soldiers have been killed since the army swung into action in late April, while the militants have carried out bomb attacks in Lahore, and the northwestern cities of Peshawar and Dera Ismail Khan.

Western allies, worried the nuclear-armed country was sliding into chaos, have welcomed Pakistan’s show of steel and the army action has received wide support from major political parties, the public and media.

“The people of Swat have realized that the entire misery which we are facing today, it is because of the Taliban, because of the terrorists, who are not only enemies of the country but enemies of Islam,” Malik said.

On Thursday, hours after Holbrooke visited Mardan district to see camps set up for some of the 2.5 million people who have fled Swat, militants shot dead five policemen and a soldier after first targeting a convoy with a roadside bomb.

Army chief General Ashfaq Kayani said his forces had snuffed out “organized resistance in Swat’s towns and along roads leading into its alpine valley, and spoke of operations on a “limited scale” to eliminate the hideouts of remaining militants, and run their leaders to ground.

“The tide in Swat has decisively turned,” a military statement issued on Thursday evening quoted Kayani as saying.

President Asif Ali Zardari has taken a strong stand against militancy, but he has to convince many Pakistanis that they are

not fighting America’s war, despite being a U.S. ally in a broader campaign to defeat al Qaeda and stabilize Afghanistan.

“It is the fight for our very survival,” Zardari said in an interview with the Financial Times published on Friday. “Future generations will not forgive us if we fail. We cannot afford to lose it. Defeat is not an option for us.”

Holbrooke had earlier announced the United States aimed to give Pakistan $200 million, in addition to $100 million already pledged, to help it deal with displaced people from Swat.

Holbrooke has said the United States aimed to give Pakistan $200 million, in addition to $110 million already pledged, to help deal with the humanitarian crisis posed by the massive dislocation of population. He has also urged European and Islamic nations to do more to help.

There is speculation that once Swat is under control, the army could switch its focus to South Waziristan, where four soldiers were killed by a roadside bomb on Friday.

The army retook Swat’s main town of Mingora last week, raising hopes that many of the displaced people will soon be allowed to return home.