Kabul, Aug 6 : At least 40 Taliban militants have been killed and security operations backed by fighter jets are underway in Shiberghan city, the capital of Afghanistan's Jawzjan province, on Friday, an army statement said. "The security forces backed by fighter planes have killed 40 insurgents and captured 15 others in a counter-offensive to foil a Taliban attack on Shiberghan city today," Xinhua news agency quoted the statement as saying. "The Taliban rebels entered houses in Shiberghan city and have been using civilians as human shield," the statement said, adding government forces would continue to target the insurgents until the city is cleared. Taliban militants, according to officials and residents of Shiberghan, entered the city on Friday morning and a gun battle has been continuing. The Taliban outfit has intensified activities and overrun around 200 districts including some in Jawzjan since early May. The group has been attempting to capture big cities including Herat, Lashkar Gah, Shiberghan and Maimana. /IANS