Kabul – Gunmen wearing security force uniforms kidnapped an American and an Australian in the heart of Kabul, officials said on Monday, the latest in a series of abductions of foreigners in the conflict-torn country.The two professors at the American University of Afghanistan were seized from their vehicle on Sunday evening. No group has so far claimed responsibility.The kidnappings came three days after a group of foreign tourists were ambushed by the Taliban in the western province of Herat, underscoring the growing insecurity in Afghanistan as insurgents intensify nationwide attacks."Two foreign professors, one American and the other Australian, were abducted at gunpoint by a kidnapping gang from Dar-ul-Aman road in the centre of Kabul city," a security official told AFP."We refrain from further comment in order to not damage police rescue efforts."The kidnappers were wearing Afghan security uniforms, another official told AFP, adding that the driver of the vehicle who was unharmed had been held for investigation.Four gunmen were involved in the abduction, according to a Western official in Kabul.The Afghan capital is infested with organised criminal gangs who stage kidnappings for ransom, often targeting foreigners and wealthy Afghans, and sometimes handing them over to insurgent groups.The US State Department said it was aware of reports of the kidnapping of an American but declined to comment further.The Australian government confirmed the "apparent kidnapping" of one its citizens, citing its embassy in Kabul, but also refused to elaborate due to security considerations."We continue to advise Australians not to travel to Afghanistan because of the extremely dangerous security situation, including the serious threat of kidnapping," the government said in a statement.Growing insecurityThis appeared to be the first reported abduction related to a private university in Afghanistan.The elite American University of Afghanistan, which opened in 2006 and enrols more than 1 700 students, was not immediately reachable for comment. It has attracted a number of visiting faculty members from Western countries.The abductions underscore the growing dangers faced by foreigners in Afghanistan.Foreign tourists, including British, American and German nationals, came under Taliban fire on Thursday in a volatile district of Herat, leaving some of them wounded. They were safely evacuated to Kabul and were flown out of the country.Aid workers in particular have increasingly been casualties of a surge in militant violence in recent years.Judith D'Souza, a 40-year-old Indian employee of the Aga Khan Foundation, a prominent NGO that has long worked in Afghanistan, was rescued last month after she was abducted near her residence in the heart of Kabul on the night of June 9.D'Souza's abduction came after Katherine Jane Wilson, a well-known Australian NGO worker, was kidnapped on April 28 in the city of Jalalabad, close to the border with Pakistan.Wilson, said to be aged 60, ran an organisation known as Zardozi, which promotes the work of Afghan artisans, particularly women.The United States in May warned its citizens in Afghanistan of a "very high" kidnapping risk after an American narrowly escaped abduction in the heart of Kabul.In April last year the bullet-riddled bodies of five Afghan workers for Save the Children were found after they were abducted by gunmen in the strife-torn southern province of Uruzgan.