A Pakistani confidence trickster has been arrested for posing as an FBI agent and defrauding unwitting customers in Islamabad of $21,000, police said Friday. Hayat Khan, 48, was detained in a sting operation on Thursday following a number of complaints in the capital, police official Suhail Akram told AFP. \"The fake FBI agent grabbed millions of rupees. He is now under arrest,\" he said. Khan, who also went by the alias Riaz Khan, claimed to have worked for the FBI and trapped his victims by offering to sell US dollars at a lower rate than on the market. He reeled them in by offering favourable exchange rates for relatively small amounts of money, say $500 or $1,000, and then overcharging them for much larger amounts. It was not immediately clear why he pretended to work for the FBI -- the US Federal Bureau of Investigation. Pakistan is awash with anti-Americanism, exacerbated by last year\'s raid that killed Osama bin Laden in Pakistan, US air strikes that killed 24 Pakistani soldiers in November and ongoing drone strikes against Islamist militants. \"We have recovered two million rupees ($21,000) from his possession and are investigating,\" Akram said. Currency exchange is an attractive business in Pakistan, where the rupee has lost 4.1 percent of its value this year and last week sank to its lowest level against the dollar. Yaseen Anwar, the governor of Pakistan\'s central bank, said last week that the fiscal deficit and lack of external financing would continue to challenge Pakistan. Uncertainty over Pakistan\'s six-month blockade on NATO supplies to Afghanistan and worsening ties with the United States have also hit the rupee, analysts say.