(Bloomberg) — Unable to retrieve their investments, users of Turkish crypto exchange Thodex have filed a complaint alleging fraud, with their lawyer saying hundreds of millions of dollars may have been stolen. The head of the exchange has been unreachable and allegedly fled the country.“We’ve filed a legal complaint on Wednesday,” Oguz Evren Kilic, who represents an unspecified number of Thodex users, said by phone on Thursday. With active users numbering about 390,000, assets that remain “irretrievable” may be worth hundreds of millions of dollars, he said. A prosecutor in Istanbul has launched an investigation, the state-run Anadolu Agency reported.Kilic alleged that Faruk Fatih Ozer, Thodex’s chief executive officer and founder, fled the country Wednesday evening via a commercial flight from Istanbul. Ozer hasn’t responded to multiple calls to his mobile phone. Demiroren News Agency said he’s gone to Albania, publishing what it said was a photo of Ozer at the airport.As authorities and customers try to work out the details of what happened to Ozer, Thodex and the money invested in it, officials are calling for rapid regulation of the crypto market. A surge in the prices of digital tokens has been accompanied by convictions globally in scams tied to crypto platforms as well as speculation that authorities will seek tighter controls.The Turkish government should take action “as soon as possible,” Cemil Ertem, senior economic adviser to President Recep Tayyip Erdogan, told Bloomberg on Thursday. “Pyramid schemes are being established in this area. Turkey will undoubtedly carry out a regulation that’s in line with its economy but also by following global developments.”Dogecoin CampaignThodex announced a campaign to boost users in mid-March, saying it would distribute millions of Dogecoins to new registrants. Its website says 4 million Dogecoins have been distributed, though many people have taken to social media to complain they never received them.Crypto Users Bicker After Turkish Exchange Abruptly Goes SilentThe suspension of operations at the exchange is due to “a partnership offer,” the company said in a statement on its website, without elaborating. Services will remain shut for “about four-five working days” while a stake sale is completed and users needn’t worry about their investments, it said.(Updates with Demiroren News Agency story in third paragraph.)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.