A bomb attack killed an Afghan intelligence agent and wounded three girls in the country's north on Thursday, a provincial spokesman said, with the Taliban claiming responsibility. Payenda Mohammad, a junior official in the Kunduz branch of Afghanistan's National Directorate of Security (NDS), died when the blast destroyed his car near his home, provincial spokesman Mahboobullah Sayedi told AFP. Three young girls were also injured, he added. The Taliban said in a text message that the bombing was aimed at senior security officials. The militia, which has fought a near 10-year insurgency since the 2001 US-led invasion ousted it from power, has stepped up targeted assassinations. Last month, President Hamid Karzai's powerful half-brother, Ahmed Wali Karzai, was killed in the southern province of Kandahar. Kandahar mayor Ghulam Haidar Hameedi and Jan Mohammad Khan, a senior adviser to the president, were also assassinated in July. International troops have started to withdraw from Afghanistan ahead of a 2014 deadline for all foreign combat soldiers to leave. But there is concern about the ability of Afghan security forces to protect their country against the Taliban-led insurgency. The north of Afghanistan has traditionally been more secure than the south and east, but a string of violent episodes has raised fears about stability. On Tuesday, three security guards were killed in Kunduz after suicide bombers attacked the offices of a security company which used to be a German-run guesthouse. And in May, northern Afghanistan's influential police commander in the province of Takhar, which borders Kunduz, was also killed.