As in most big cities, pickpockets gather wherever there are large crowds of tourists. There are also a few scams around. Over the last few years there have been an increasing amount of reports from foreigners who have been robbed by bogus police. Men who claim that they are plain-clothes police investigating counterfeiting or illegal money-changing approach tourists and ask to see their money, which is returned after being examined. The unsuspecting tourist finds out later when they check their wallet that a substantial amount of money has been taken. Another ploy involves a 'lost tourist' asking for directions (usually in halting English). Once you have been in conversation for a few minutes, two of the tourist's 'friends' interrupt, claiming to be plain-clothes policemen and accusing you of changing money illegally. They will demand to see your wallet and passport, but if you hand them over they are likely to run off with them. If in doubt, insist on accompanying them to a police station.