A suicide car bomber killed 10 people in north-western Pakistan yesterday, including four children, two police officers and a woman, officials said.

At least 25 others were injured.

The blast at a police checkpoint on the outskirts of Peshawar was the latest in a string of militant attacks targeting the city.

Attacks on security forces, civilians and Western targets have surged since the government launched an offensive in mid-October against militants in the border region of South Waziristan, where al-Qaeda and Taliban leaders are believed to be hiding out.

Peshawar has been a main focus of the attacks, which in the past week alone have killed more than 50 people, including 10 at the regional offices of Pakistan's top intelligence agency, which was targeted by a massive truck bombing on Friday.

The agency, called Inter Services Intelligence, has been overseeing much of the country's anti-terror campaign.

Security was tightened in and around the city after Friday's attack.

Police were manning checkpoints at all entry points to the city and were checking every vehicle, said local government official Sahibzada Mohammad Anis.

"Suddenly, a car exploded with a big bang," said police official Malik Jehangir, who was working at the checkpoint.

"There was a long queue of the vehicles. One of our officials wanted to search the car when it exploded."

Taliban and al-Qaeda fighters are waging a war against the Pakistani government because they deem it un-Islamic and are angry about its alliance with the United States.

The insurgency began in earnest in 2007, and attacks have soared since preparations for the offensive in South Waziristan began.

The government has vowed that the militant attacks will not dent its resolve to continue the operation in the region, where officials say the most deadly insurgent network in Pakistan is based.

The army claims it is making good progress.