At least 49 people have been killed in a bombing in a crowded area of the north-western Pakistani city of Peshawar, officials say.

More than 100 people have also been injured in the suspected suicide bombing, a regional minister said.

Officials said a vehicle laden with explosives had been detonated near the city's Khyber Bazaar.

Friday's explosion was the latest in a series of recent bombings across north-western Pakistan.

ANALYSIS M Ilyas Khan, BBC News, Islamabad The renewed Taliban campaign coincides with increased speculation about the start of a major ground offensive in South Waziristan - the epicentre of militancy in Pakistan. This shows a change of tactics. Instead of spectacular attacks against military, police, sectarian or Western targets, militants are focusing on low-intensity bombings to cause general terror. The bomber used less than 50kg of explosives, laced with bearings and shells to cause maximum damage in a crowded civilian location. It could also indicate a decline in the ability of the militants to penetrate high-value targets with large bombs.

It comes as the Pakistani army prepares an operation against the Taliban in the tribal region of South Waziristan.

TV footage showed what appeared to be the charred frame of a bus destroyed by the explosion. Many of the victims of the blast were thought to be passengers and police said this included a number of children.

The remains of other vehicles were strewn in the road.

Officials said they thought a suicide bomber travelling in a car had carried out the attack.

"He blew himself up as the car was next to a passenger bus passing through the market," senior police officer, Shafqat Malik, told the BBC.

It is the deadliest attack in Pakistan since March when a suicide bomber destroyed a crowded mosque in Jamrud, killing at least 50 people.

But doctors at the Lady Reading hospital, close to the blast site, warned that the toll could rise as many of the injured were in a critical condition.

Pakistani officials emphasised the government's resolve to tackle militancy on a wider scale.

"One thing is clear, these hired assassins called Taliban are to be dealt with more severely," Interior Minister Rehman Malik told reporters.

"I think the incident of today has accelerated this," he added. "We think we have no other option except to carry out an operation in South Waziristan because every matter, every incident, whatever is happening, all roads are leading to South Waziristan so I think we'll have to proceed."

Vehicles torched

A witness at a local hospital told the Associated Press news agency that he had seen the vehicle explode.

"I saw a blood-soaked leg landing close to me," he said. "I understood for the first time in my life what a doomsday would look like."

Witnesses also described how bystanders desperately tried to free survivors trapped in vehicles overturned by the force of the explosion.

Hours earlier, police said gunmen in Peshawar had attacked vehicles being used to take supplies to Nato forces in Afghanistan, setting them on fire and destroying them.

Correspondents say there have been increasingly frequent militant attacks after a lull following the death in a missile strike of top Taliban commander, Baitullah Mehsud.

The blast comes days after a deadly bombing at a UN office in the Pakistani capital, Islamabad, and less than two weeks after a double suicide car bombing in Peshawar.

The BBC's Aleem Maqbool reports from Islamabad that the Taliban has been threatening to carry out attacks unless operations against the militant group were stopped.

He says that in recent days Taliban positions in the tribal areas have been bombed by the air force, amid speculation that the army's offensive is soon to be intensified.

There was a period of relative quiet in August after Baitullah Mehsud was killed, but the rate of attacks claimed by the group has increased since then, our correspondent adds.