A Taleban militant group claimed responsibility Monday for a suicide bombing that killed at least 11 people at the gate of an army base in Pakistan's volatile northwest. The attack Sunday in the city of Mardan was the deadliest in more than two months and could complicate efforts by the new government to reach peace deals with militants. Four soldiers were among the dead. Taleban spokesman Maulvi Umar said the attack was carried out by a branch of the militant group Tehrik-e-Taleban in response to a Pakistani military operation in the nearby district of Darra Adam Khel. “We have said time and again that the Pakistani government should stop such activities because we are in negotiations with the government and such acts can harm these negotiations,” he said. Umar also described the bombing as a response to a suspected US missile strike last week in the Bajur tribal region that killed at least 14 people. Sunday's bomb went off in a market between a bakery and the gate of the Punjab Regimental Center in Mardan. Police chief Akhtar Ali Shah said 11 people were killed and 22 wounded. Maj. Gen. Athar Abbas, the army's top spokesman, said four of the dead were soldiers guarding the gate of the base, which appeared to have been the target. The bomber blew himself up when he was stopped by one of the soldiers, “I was busy dealing with a customer when a big bang shattered everything,” said Ehsanullah Khan, 25, who works in a music shop in the market and helped take wounded people to hospital. “A piece of broken glass left a deep cut on my arm, and I rushed out in panic.” “I pulled away three people with bleeding wounds lying in the road,” Khan said. Pakistan's northwest is considered a haven for militants with links to the Taleban and Al-Qaeda, many of whom are determined to drive US forces out of neighboring Afghanistan. The new government, in power some seven weeks, has sought peace deals with some militant groups, a step away from the more forceful tactics of President Pervez Musharraf, a former army chief and longtime ally of the United States in the war on terrorism. US officials have warned such deals could just give time for militants to regroup. One of the militants' demands has been the withdrawal of the army from parts of the northwest, where tens of thousands of troops have been deployed to fight extremists. Attacks had subsided overall since the new civilian government came to power, though they had not entirely disappeared. Just last month, a car bomb near a police station in Mardan killed three people, including a policeman. The latest attack appears to be the worst in the country since a pair of suicide bombings in mid-March killed 27 people in Lahore, a normally peaceful city in Pakistan's east.