PESHAWAR, Pakistan — A suicide car bomber attacked a police checkpoint in northwest Pakistan on Saturday, killing 11 people, including four children, the latest in a wave of militant attacks that have claimed more than 300 lives in the past month.

The attack on the outskirts of Peshawar solidifies the city's ominous status as a primary target for militants trying to force the military to end an offensive against their associates launched last month in the border region of South Waziristan, where al-Qaida and Taliban leaders are believed to be hiding.

Strikes in the past week alone have killed more than 50 people in the city, including 10 at the regional office of Pakistan's top intelligence agency, which was targeted by a massive truck bombing Friday. The agency, the Inter Services Intelligence, has been overseeing much of the country's anti-terror campaign.

On Saturday, a Taliban commander claimed responsibility for that attack and another targeting a police station the same day in neighboring Bannu district. He vowed the violence would continue.

"The suicide bombers were trained by me and I have a lot more volunteers to carry out more attacks," Qari Hussain Mehsud told an Associated Press reporter by telephone. The reporter had met the commander in the past and recognized his voice.

Security was tightened in and around Peshawar after those attacks. Police were manning checkpoints at all entry points to the city and were checking every vehicle, said a local government official, Sahibzada Mohammad Anis. It was one such checkpoint that was struck Saturday.

"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 vehicles. One of our officials wanted to search the car when it exploded."

Liaqat Ali Khan, the city's police chief, said 11 people were killed, including two police officials. Four children and a woman were among the dead, while another 25 people were wounded, he said.

Taliban and al-Qaida 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 spiked since preparations for the offensive in South Waziristan began.

The U.S. has urged Islamabad to persevere with its campaign against the Taliban, especially in South Waziristan because militants have used the area as a base to attack Western troops across the border in Afghanistan.

Prime Minister Yusuf Raza Gilani said the terrorist attacks would not derail the military campaign.

"They are doing it to divert our attention," he said. "We have the ability to deal with them."