By Daren Butler and Ali Kucukgocmen
ISTANBUL (Reuters) -Turkey detained dozens of people in an investigation of a cryptocurrency trading platform and sought its founder's arrest in Albania, police said on Friday, after Turks filed criminal complaints saying they had been scammed.
The Thodex platform, which had been handling daily cryptocurrency trade worth hundreds of millions of dollars, said on its website on Thursday it would be closed for four to five days due to a sale process.
But users who have not been able to withdraw money or access their accounts voiced concern on Twitter that they may have been defrauded, comments widely picked up by Turkish media.
Police launched raids at 6 a.m. (0300 GMT) across eight provinces on Friday with warrants to arrest 78 suspects, Istanbul police said in a statement. A day earlier they searched the company's Istanbul offices and seized materials.
Sixty-two people have been detained so far, the state-owned news agency Anadolu reported.
Istanbul police said the company's founder and CEO, Faruk Fatih Ozer, had flown to the Albanian capital Tirana on Tuesday.
Interpol issued a red notice for Ozer on Friday after a request by Ankara. Turkey's interior minister and police chief spoke with their Albanian counterparts on Thursday to seek Ozer's arrest, Turkish police headquarters said.
Reuters was unable to reach Ozer or his lawyer for comment.
An Istanbul prosecutor's office on Thursday said it began an investigation into Thodex amid claims that the platform had led to the "aggrievedness of many citizens". Turkey's financial crimes investigation board MASAK blocked the company's accounts on Wednesday and began an investigation, a MASAK source said.
Thodex said "negative" media reports about it were untrue, and that banks and funds - which it would identify later - wanted to invest in the company and had proposed a partnership.
The 24-hour trading volume on Thodex was $538 million on its last trading day, according to Coinmarketcap.
Last week, Turkey banned the use of crypto assets for payments, adding to factors that sent bitcoin down 14% at the weekend. Turkey's central bank cited "irreparable" damage and transaction risks as reasons for the ban.
(Additional reporting by Ali Kucukgocmen; writing by Daren Butler; editing by Nick Macfie, Larry King)