The financial crimes units of the Turkish National Police carried out operations in 29 cities early Tuesday in a crackdown on a major export scam. Some 40 people were detained, including three civil servants, while more than 50 people are being sought in the operations.Media outlets said the suspects are accused of "fictitious exports" worth about $1 billion and the crackdown was the culmination of a string of surveillance operations over the past three years.The names of the cities other than Istanbul where operations were underway were not disclosed as the news went to print. In Istanbul, the country's financial hub, police launched simultaneous operations in the districts of Beşiktaş, Sarıyer and Tuzla.Media outlets reported customs officers and a deputy manager at an Istanbul tax department were among the detainees. The suspects are accused of issuing fake receipts on behalf of 12 shoe manufacturing and textile companies for the fraud. They are also accused of declaring false exports by disguising the transfer of goods tourists purchased in Turkey as mass exports.Export fraud, known in Turkish as "hayali ihracat" or fictitious export, was common in the 1980s and has apparently made a comeback with incentives for exports. The fraud involves inflation of costs for exports as well as claiming a refund of value-added tax reimbursed by the state, by fabricating documents showing the exports has taken place. A relatively new scheme involves importing goods for their export to a third country. Importing companies do not have to pay high fees for imports as the goods are not sold in Turkey, but scammers sell the imported goods in Turkey to dealers on the domestic market. Last year, police detained and arrested dozens of people in Istanbul in operations against export scams involving textiles.