"Business is booming, I have made good profits since the Taliban were ousted," said a smiling Sayed Habib as he showed Western dresses to young women in one of Kabul's glitziest shopping malls. Habib, 34, is one of a new generation of rich young Afghans driving flashy cars and wearing designer labels who have made fortunes in Afghanistan's war economy since the US-led invasion 10 years ago. His shop is one of many signs that some in the Afghan capital are now very wealthy -- although Kabul's mirrored glass malls and lavish mansions often sit on dusty roads dotted with children begging for money, highlighting wider, ingrained poverty. And despite their wealth, many of the city's yuppies are worried that the withdrawal of US-led combat forces in 2014 will mean security declines and the economic boom turns to bust. "Not only me but every investor I know expects the bubble that created this economy will burst as soon as foreign aid is cut or when foreign troops leave in 2014," said entrepreneur Ahmad Lais. Afghanistan receives around $15 billion annually in security and civilian aid from overseas but the figure is set to fall sharply as troops withdraw. A US Senate committee report in June warned this could trigger "a severe economic depression". Thousands of Afghans -- many in Kabul but also in the rest of Afghanistan -- are employed to work with the NATO-led military force and other international organisations or, like Lais, have set up businesses to provide for them. Many more, including Habib, have seen their firms thrive as these Afghans spend their disposable income. Such pockets of wealth in what remains one of the world's poorest countries were unthinkable under the Taliban, whose imposition of a strict version of sharia law after a devastating civil war left little room for economic growth. Lais has two houses in Kabul, dresses in smart, Western-style suits and drives a brand new Toyota Land Cruiser, the favoured vehicle for wealthy Afghans and expatriates. "I came back to Afghanistan as soon as the Taliban regime collapsed," he explained. "Our company won a contract to supply fuel to international troops. I used the profits I made to open two new factories and employed 150 workers. "My factories produce construction materials that are used in thousands of homes that are being built in Kabul." But his fuel supply business is currently not doing well, he said, because contracts from NATO forces are drying up and the security situation is deteriorating. The United Nations has said violent incidents in the war rose 39 percent in the first eight months of this year, although the NATO-led foreign force in Afghanistan disputed this, saying attacks were down two percent. Khan Jan Alakozai, deputy head of the Afghanistan Chamber of Commerce and Industries, said foreign troop withdrawals which got under way in July this year had already prompted some investors to flee. "When Obama announced all troops will be pulling out, our international business partners, many of them Westerners, began preparing to leave the country," he said. "We try to assure them that it will not be risky to make investments here, but they come and they see the situation, they see that even the US embassy in Kabul is not that safe." The comment was a reference to a 19-hour attack last month which saw militants launching rocket-propelled grenades at the American mission in Kabul, one of the capital's most tightly-guarded sites. Alakozai added that while pulling out foreign troops might be a good move politically for countries fighting an unpopular war, it could be disastrous for Afghanistan's new generation of businessmen. "At this stage, Afghan security forces cannot be trusted," he said, referring to the 300,000-strong Afghan force being handed increasing control of security as foreign troops leave. "Everybody invested in Afghanistan trusting that the US and NATO forces would stay here for the long run. But if they leave so soon, it's no longer safe for the business community to invest in Afghanistan." Another young Afghan entrepreneur, car dealer Haji Zabiullah, echoed many of his wealthy countrymen by suggesting he could take his wealth elsewhere, for instance Dubai, if the economic and security situation gets too bad. "I might have to transfer my investments to another country if the Americans leave," he said. The vast majority of Afghans, who remain dirt poor and locked into a predominantly agrarian economy, do not have that option.