PESHAWAR: A bomb blast ripped through a Pakistani bus on Friday, killing 19 people, including seven women and a child, on the outskirts of the northwestern city of Peshawar, police said.

More than 40 others were wounded in the attack on a bus rented by the government to take staff home after work in the province of Khyber Pakhtunkhwa.

It was the deadliest attack in months on Peshawar, which has long been a flashpoint for a local Taliban insurgency targeting government officials, security forces and ordinary civilians.

The city runs into the semi-autonomous tribal belt that US officials consider a safe haven for Al-Qaeda and insurgents fighting both in Pakistan and across the border in Afghanistan.

The explosion went off in the Daudzai area, killing government employees and other private passengers riding the same bus, officials said.

"The bomb was planted under the bus," provincial information minister Mian Iftikhar Hussain told reporters.

"We still can't say how many government employees and private passengers were killed, but there were heavy human losses," he added.

Police official Tahir Ayub told AFP 19 people were killed and more than 40 wounded. Another police official, Shafiullah Khan, said seven women and a girl, aged seven, were among the dead.

The explosion destroyed the back end of the bus. Bloodied pieces of human flesh littered the seats, along with blood-stained clothes on the road lined with juniper trees, an AFP reporter said.

Muhammad Ullah, 48, a police official on the bus, said there was a deafening blast.

"The explosion triggered massive smoke inside the bus but even then we could feel soft and bloody pieces of human flesh hitting our bodies," Ullah told AFP while being treated for head and shoulder injuries.

Arsalan, a junior clerk in the provincial auditor general's office, said he remembered asking the driver to stop at a mosque on the road for main Friday prayers then the explosion took place.

"I don't remember what happened next because I fainted and came round in a hospital bed," the 28-year-old, also with head and neck injuries, told AFP.

The attack came one day after a remote-controlled bomb killed at least 15 people outside a madrassa in Pakistan's southwestern city of Quetta.

The country of 180 million sits on the frontline of the US-led war on Al-Qaeda and since July 2007 has been gripped by a local Taliban-led insurgency, concentrated largely in the northwest.

In the last five years, attacks blamed on Islamist bombers have killed more than 5,000 people according to an AFP tally.

Pakistan's relations with the United States are in disarray and for the last six months, since US air strikes killed 24 Pakistani soldiers along the border, it has imposed a blockade on NATO supplies crossing overland into Afghanistan.

On Thursday, US Defense Secretary Leon Panetta warned Pakistan that the United States was running out of patience over Islamabad's refusal to do more to eliminate safe havens for insurgents who attack US troops fighting a 10-year war against the Taliban in Afghanistan.

Panetta made the strong remarks after talks with Afghan Defence Minister Abdul Rahim Wardak on the latest leg of an Asian tour that took him to Pakistan's arch-rival India, but not Islamabad in a sign of dire US-Pakistan relations.

He singled out the Haqqani network, a Taliban and Al-Qaeda-linked faction that has bases in Pakistan's lawless tribal district of North Waziristan and which has been blamed for some of the deadliest attacks of the 10-year war in Afghanistan. AGENCIES