PESHAWAR: A suicide bomber on Monday blew up a car packed with explosives near a college in Peshawar, killing four people in the latest attack on a Pakistani city beset by Taliban-linked violence.

The bomber struck in a suburban road as children were going to school in the northwestern city, devastating a mosque, destroying two rooms at a boys' college and bringing down one wall of a police station, witnesses said.

It was the fifth suicide attack in eight days to hit the sprawling city of 2.5 million people, which lies on the edge of Pakistan's lawless tribal belt, where US officials say Al-Qaeda militants are plotting attacks on the West.

Attacks in the northwest have soared as 30,000 Pakistani troops press into Taliban strongholds in the hostile terrain near the border with Afghanistan, where 100,000 NATO and US troops are fighting a deadly insurgency.

"The death toll is four and there are 26 injured," doctor Zafar Iqbal of the Lady Reading hospital told AFP. One child was among the dead and four children were among the wounded.

Witnesses said a vehicle sped towards the police station and exploded nearby, leaving much of the building in ruins as ambulances raced through the streets of the densely populated suburb of Budh Ber.

Teacher Mohammad Shahid said he had just dropped off his children at school when he heard a deafening blast, which left a crater five feet deep and nine feet wide (about 1.5 metres and three metres).

"I looked back and saw parts of a vehicle flung in the air and then the body of my neighbour fell on the ground near me. It was a horrible sight," he said.

Javed Khan, who drives a horse-drawn cart, said the car had sped towards him, forcing him to leap out of its path, before the explosion hit.

"I fell on the ground. Shrapnel hit my forehead. I saw debris all around and people crying for help," Khan said.

Provincial police chief Malik Naveed told AFP that three paramilitary personnel deployed outside the police station were wounded.

"A chain barrier was placed to close the road leading to the police station. Our three Frontier Constabulary men, who were trained snipers, were posted there and got injured in the blast," he said.

"When the bomber broke the chain with his vehicle, one of the snipers fired at him and he was injured. That is why he could not reach close to the police station."

Pakistan's security forces are on the front line of a deadly Al-Qaeda-linked campaign that has killed more than 2,530 people in 28 months in the nuclear-armed Muslim country and has recently increased in intensity.

Prime Minister Yousuf Raza Gilani ruled out talks with militants, telling the National Assembly on Monday evening: "Negotiations are held with humans and not with beasts."

"They (the militants) are killing innocent humans," he said, adding that the operation would continue to "fully secure" the nation.

Although there was no immediate claim of responsibility for Monday's attack, the Tehreek-e-Taliban Pakistan (TTP) has vowed to attack in the cities to avenge a military assault on its South Waziristan stronghold, now into a fifth week.

The TTP claimed responsibility for a suicide car bombing that killed 15 people in Peshawar on Saturday and the bombing of the Peshawar headquarters of the nation's top intelligence agency, the ISI, on Friday that killed 17 people.

Militant attacks, which have started to inflict mass casualties in civilian targets such as market places, have killed more than 450 people -- most of them in Peshawar -- since early October.

Pakistan launched 30,000 troops into a three-pronged offensive into South Waziristan on October 17, an operation that has been strongly endorsed by the United States, which aims to crush the TTP leadership and its strongholds.

Security forces continued their operation on Monday and secured heights south and went of the village of Janata near Sararogha, a military statement said.

On Sunday, about 50 militants from the banned Lashkar-e-Islam extremist group stormed the home of Fahimuddin, a local mayor who had raised a militia to fight the Taliban, in Bazid Khel village on Peshawar's outskirts.

Karim Khan, a senior police official in Peshawar, said three militants were killed in the clash with Fahimuddin's militia. The rest fled the scene.

Lashkar-e-Islam (Army of Islam), which has loose ties to the TTP movement, enforces prayers five times a day and punishes people accused of prostitution, gambling and other vices.